One midi sequencer that is rarely mentioned is The Jazz Midi Sequencer. It uses a piano roll interface, and is pretty powerful for a free tool. While I tend to use Anvil Studio for basic composing if possible (and sometimes break into the Event editor to use the effects that they make you pay extra for), Jazz makes it much easier to use effects like pitch bend, vibrato, LFO effects and what-not. I think it actually has all the standard midi features available to you.
I haven't used any midi trackers, though, so I couldn't really compare them. I still have the old installer zip file for Jazz 4.0.0 and 4.0.3 from before they went open-source compile-it-yourself. Jazz 4.0.0 works great in WINE, if anybody cares. Just have to have Timidity or what-not, of course.
Interface takes some getting used to, but once you do, you'll be flying if you don't mind piano roll.