(ADDITIONAL NOTE: Noteworthy did not pay me to write this.)
If you are a musician in today's world, you use music notation software. That is a given. You may still use staff paper and a pencil to write down your ideas, or even to compose whole pieces; but if you are going to share them with the world, the world will expect the scores you produce to be computer-engraved. From this it follows that, when musicians gather, sooner or later the conversation will always get around to the same question: Which program do you use? Or, more likely - especially if you are a composer or an arranger - to a more pointed variant: Do you use Finale, or Sibelius? Because if you are serious about writing music, it is always assumed that you will be using one or the other of these two highly complex $600 packages; although there are many other options out there, nothing else is considered quite adequate for serious work.
If you are a composer or arranger, though, I have news for you: it turns out that, for what you and I do, it is actually Sibelius and Finale that are not quite adequate.
Sibelius and Finale are basically music engraving programs. They turn out superb printed music, but turning out printed music and notating musical ideas from scratch are not the same thing. The workflows of music engraving and music composition are vastly different. And there is only one program I know of that takes that difference into account: a little-known $50 package called NoteWorthy Composer.
The two big-name programs - and their free open-source clone, MuseScore, and the new kid on the block, Dorico (a highly touted project of a group of former Sibelius programmers), and everything else I've looked at recently - are score-oriented. They think downward: the staff is considered a subdivision of the score, the measure is a subdivision of the staff, the beat is a subdivision of the measure. Notes, dynamics, etc., are hung on this pre-existing framework. NoteWorthy, by contrast, is object-oriented; it thinks upward. A staff is a string of objects; a score is a string of staves. The music is built from the bottom up rather than being filled in from the top down. And this makes a huge difference in the way you work.
In other programs, you start with a score full of measures with rests in them and substitute notes for the rests. (Dorico appears to hide this process, but it's still there under the surface: the framework is merely invisible.) One result of this is that, in these programs, note entry, editing, and score layout are all separate processes, which you must switch between. Barlines are set in advance; notes fill up a measure until they hit the right-hand barline, then spill over into the next measure. Once entered, a note is tied to its beat until you switch to editing mode. Think of it as putting things into containers, which are inside other containers. To make any significant changes, you have to make changes to the containers as well. That's why editing mode is necessary.
In Noteworthy, you start with a blank staff and just toss objects onto it. Everything in the score is an object. Notes are objects; barlines are objects; instrument changes and clef changes are objects; dynamics and time signatures and tempi are objects; everything. This means that they can occur in any order, and can be placed at any point in the score at any time. You're stacking things up, not putting them into containers. It's very much like writing by hand on staff paper, but without the need of an eraser. Jot down notes in a hurry; throw in barlines and dynamics as you write, or go back and put them in later. The program doesn't care. If you want to put a 5/4 measure in the middle of a 4/4 score, go ahead and write the notes that way, then go on - you don't have to put the time signature in until you're ready to print. You don't have to put the barlines in, either: you can put down your notes in a rush of inspiration and put the bars in later (NoteWorthy has an "Audit Barlines" tool that can help you with this). Need to change a note from a quarter note to a half note, 18 measures back? Just select the note and change it. No need to switch to a separate editing mode: everything later in the score simply bumps over to make room. Ties, slurs, accidentals, articulations, etc., are treated as properties of objects, and can be changed at any time. In fact, just about any property of any object can be changed at any time. Just select the object, press [Alt][Enter] to bring up the "Properties" dialogue, and have at it. This may sound a bit chaotic, and it is, but it's far closer to what we do with pencil and score paper than hanging notes on the framework of a pre-existing idealized score will ever be.
Another way in which NoteWorthy's object-oriented architecture seems to me to be superior to its more famous (and more expensive) brethren lies in the way it handles layers. In other programs, layers are seen as attributes of the staff they are constructed for; they are used for separate voices, and you are limited to four layers or fewer. In Noteworthy, layers are actually separate staves: they can be used for anything, and you can have as many as you want. This has the disadvantage that collisions between objects on different layers are not automatically handled, but must be hand-adjusted. The tradeoff is an incredible amount of flexibility. You can do just about anything with layers. You can create slurred notes with the notes on one layer and the slur on another (this actually has some uses in preparing printing layouts). You can copy layers from one staff to another: in this manner, one layer can be made to serve several similar compositions. A layer can be assigned to a different MIDI channel than the one used by the staff it is layered with. Want to add a flute descant to a choral work, but adding a descant staff forces extra pages in the printout? Layer the descant with the soprano, or with the treble part of the accompaniment. The two parts can appear on one staff in the score, and MIDI playback will remain accurate.
A first look at NoteWorthy might make it seem pretty bare-bones: there are some important things that it doesn't handle natively, including basics such as 8va notation, arpeggios, cue notes, and trills and tremolo markings. Skipping over the program on that account, however, would ignore the large number of plug-ins that have been created for it by its small but extremely dedicated user base. (True to its object-oriented architecture, NoteWorthy calls these "user objects" instead of plug-ins.) Almost anything the program can't do by itself, including everything I just mentioned, can be handled by already-existing plug-ins - and if you find something that can't be, just mention it on the users' forum and chances are good that a new plug-in that handles that particular problem will be created within the next week. (Yes, turnaround is often that fast.) Once entered, a user object is just another object, and can be manipulated exactly like the program's native objects. Unlike the plug-ins for some programs, integration of these is perfect. They can even be assigned to their own toolbar buttons.
Printout works well and looks good. The program's parser accurately synchronizes beats and subdivisions of beats across systems; barlines line up properly on measures with the same number of beats in them, but offset without problems if, say, one staff is in 3/4 and an adjacent staff is in 4/4. Various objects and object properties are available for changing the spacing between notes; between notes and accidentals; between staves; or between systems. You can also change the number of staves in a given system or group of systems; specify where new systems or new pages should start; and make just about any other casting-off adjustments that need to be made. A feature I particularly like is Noteworthy's ability to turn off justification in Print Preview. This allows you to see which systems have extra space in them, making it simple to decide where to change the spacing to allow easier page turns or to get rid of orphan measures at the end of a score.
The program isn't perfect. It is only available as a Windows application; Mac and Linux users have to run it through Windows emulators. The interface is quirky. ([Ctrl][a], for example - which you might expect to select an entire staff - adds a new staff instead). The view in the editor is always of one long, continuous system; if you want to see what the music will look like as a score, you have to go to Print Preview, and although NoteWorthy is richly supplied with keyboard shortcuts, Print Preview isn't one of them. Because each object is placed by hand, you also have to adjust most of them by hand: the program takes care of note and bar spacing, but nearly everything else is up to you. Program development is slow. The software has been around for more than 20 years (my earliest score written with it dates from 1996), but version numbers are only up to 2.75. The development team is secretive, but regular users of the program's forum have come to believe that "team" is probably a misnomer. NoteWorthy Composer appears to be the product of just one person, a shadowy persona known on the forum only as "Eric." This goes a long way toward explaining its quirks and its slow development speed. It also means that you are looking at a labor of love. Consider it accordingly.
I often find myself swearing at NoteWorthy, but I also swear by it. For me, the advantages of its object-oriented approach far outweigh the shortcomings. Professional music copyists might want to look elsewhere; but if you are a composer, or an arranger, or just somebody who wants to jot down tunes, I urge you to give NoteWorthy a try. I think you will be pleasantly surprised.