I was looking for the best way to synthesize drums a few months ago, and while I tried
various samplers and synths, I decided that my ultimate drum machine would be a tracker.
The tracker interface cannot be beaten for the rhythmic purposes. Plus it has perfect
timing since you don't depend on MIDI.
I'm currently using the hydrogen drumkit samples for that. Mainly the 909s which sound
good enough.
Also, for the arrangements of my band I'm starting to use rosegarden
+linuxsampler, which I load GMaq's 4pc drumkit sf2.
Since the drum timbres don't usually change a lot during performance, this options
plus some effects should be good enough (chibitracker comes with reverb and cheesetracker
has built in ladspa).
If you want to make your own drum piece timbres, I'd recommend you to use audacity to
draw your samples. You have access to all the LADSPA and nyquist plugins, and it's a
really comfortable tool to work with short samples (I'm thinking of the envelope
editor function which I love).
Good luck, and tell us the option you've taken.