I think Reaper is great option, as suggested (though it might not be the best if you're placing notes manually).
For a long time I've used FL Studio, and the thing is now I
want to try other DAWs but I can't find a Piano Roll that matches FL Studio! Every other aspect of it I could drop in favour of another DAW, but the Piano Roll is very fluent for quickly inputting notes. My tracks have all sorts of time signatures, and I've got used of lining up everything manually without being able to set time signatures in FL. Other DAWs would allow for more organisation in terms of time signatures, though this shows you can still make it work with FL.
I enter in notes manually without a musical keyboard, so something I do for realism (and to be honest, I don't know how well it works) is turn off the grid completely. Then I change the project timebase to be 384 PPQ (pulses per quarter note) - you can even go higher. The higher you go the less performant your DAW will be. Increasing this allows you to place notes at more intervals (to allow for more natural timing). For some strange reason FL starts at 96 PPQ which I believe is very low. Having said that, this "no grid" concept can also be a distraction - so maybe don't worry about this. Just thought I'd mention it regardless
Obviously variation in note volume and even in whole sections of the music help with dynamics (I have to work on this myself)
If you can get away with a cheap or a free DAW, then don't consider upgrading. It's a mistake to think that the quality is with the DAW itself, they largely work in the same way.
This is very true.
A search for better sound fonts or soft synths, or experimenting and making your own, can also take you were you want. But I will admit that there is so much on the market that it's frustrating to decide what you need, and you can keep plugging one instrument after another forever for sound that is just right.
What makes things worse is when you're composing you get so used of your own music that you feel compelled to change things - just because it begins to sound boring. And the longer you spend on a piece... the worse this gets!! At least this is the case for me.
But I think to invest money would be worth it. Where could I use it best? Should I buy a better DAW or better sounds?
lmms Studio might just work fine as a DAW as long as you have no trouble running VSTs that you'd like to use.
Hmm, maybe the sounds aren't as important at the moment as other's have said, though I'm still trying to work out what to get myself in terms of high quality Orchestral sounds.
Currently I use Garritan Personal / Instant Orchestra,
and I should say this is not the best library in terms of sounds
You really have to work with it to figure how to make it sound best.