I've always sworn by NoteWorthy Composer, although perhaps not in isolation.
It's great if you want to meticulously enter every note (although of course you can copy and paste). That lends itself to the same level of detail that classical composers went to; you can end up with a composition without a single note out of place. This is in contrast to typical sequencing software where you define blocks of notes that later get visualised as black boxes and can then be copied around and transposed and so on. If you're not careful with those programs, you can end up with a loop that sounds cool, and then you decide you want a new chord and you do it, but the melodic elements of the loop don't get joined up properly. For example.
It's also nice to have everything presented clearly in musical notation, rather than either glorified hex (trackers) or hidden away inside black boxes (typical sequencers). If you're trying to get multiple parts to sound good together, you never have to memorise what you've written for the other parts, because it's right there.
Another thing that's nice about NoteWorthy Composer is that it doesn't contain any 'magic'. Everything you do feels well specified and predictable, just like in programming. Also, for the most part, everything you do is specified directly on the source data; you never make a tweak on anything 'generated' and then find it gets horribly disrupted when you change something. This all makes me trust it more than I would trust Sibelius (possibly the only giant I've tried in fairness).
There are downsides. It always seems to lack those one or two little extra things you want. For me, the main things still missing (that I can think of) are trills, 8ve marks and n-tuplets where n isn't 3. (Multi-bar rests were recently added; double accidentals were added not long after we first bought it.) Development of new features is always very slow.
It does have a human-readable text format and user tool support though, so if you get into it, there are usually ways to hack the features you want. Before multi-bar rests were added, I still managed to download a font with the necessary symbols, and write my own tool to fake them.
Finally, the developer has always been exceedingly generous with how long the licences last. My mum bought it for me nearly 20 years ago, and I've only ever had to buy one upgrade. I don't think we've spent more than $50 or $60 in total.
If you're aiming to produce printed music, NoteWorthy Composer certainly gets the job done with the caveats described above. If you're aiming to produce computer music, then its playback (and MIDI export feature) supports all the articulations (staccato etc.) and does so very consistently. It's mechanical but at the same time rather well tuned, so, if you're just getting started, it will give you something pretty nice and solid - as if the performers involved have flawless technique. But if you want to make it sound expressive, then it doesn't really do it. I have in mind that next time I want to do that sort of thing, I will probably plan it all in NoteWorthy Composer and then use some other methodology to make a performance of it. The first thing I'll try is using my MIDIBoard with the East West virtual orchestra, but it'll be interesting to see if I end up with shoddy timing and unreliable articulation that way.
Mark, do you have an opinion on the look of the printed page with this one?