Pretty sure I tried out LMMS, but don't recall anything specifically. The main ones I looked at and stuck with for a while were Ardour, Rosegarden, plus Audacity which is more of a sound editor. Just found out on this very thread about Non, which looks promising, so that's one I'm going to try next.

I want to say the main problems are: having to set up Jack and switch between that and PA - why isn't there one sound system? - the whole USB midi routing situation, software with obscure UIs, and software that crashes. Apart from the first one these are all fairly easily solvable.

These days I mostly write stuff using synths. The Deluge for example has enough built in that you don't need to use a DAW at all.