The best drum synth is Microtonic by Sonic Charge.
I don't have it.
Microtonic's interface has always made me avoid it. I'm not into its graphics, colour scheme, even the feature set strikes me as limited. But it's still there, and still gets updated, and it's part of a creative ecosystem, the latest addition to which is actual hardware in the form of Teenage Engineering's PO-32. Sonic Charge, as a tiny company, are doing so well in managing this little software drum synth.
I have tried a few alternatives in the past - both synths and samplers. Here they are:
Pretty decent for 2001, except it took forever to release a Mac OSX version, by which time, I had given up on it.
Painful to look at.
WTF UI from Logic's "inspired" period.
Sadly, Battery appears to be a Native Instruments Kontakt instance under a different, and buggy, interface. Version 3 had an abysmal browser and poor drag&drop, and while V4 made things better, it crawls on my reasonably powerful desktop computer, and opening the plugin usually triggers all pads at the same time. Ouch.
DrumSpillage 2, Elecktroid
My worst investment to date. Reasonable UI, but both buggy and look like no longer being developed. Poor communication from developer. Still waiting on promises. I hate developers abandoning paid products. It's not right. Won't even link to website.
Tremor is the monster drum synth. Generous tone model, extensive modulation, built-in effects that help with individual sounds, multitrack routing, Amazing sequencer, direct MIDI learn, granular presets, all under a very reasonable UI. And yet, the recent update to Logic Pro 10.3 killed it. The worst in this experience has been FXpansion's response to my questions, my least favourite being "it is currently in testing to ensure compatibility/stability" 17 days ago now, and on the back of another 6-weeks-long "ASAP". If this was an issue with Logic, just blame Apple. In any case, how about not lying to customers?
Vice, a little sampler by New Sonic Arts wouldn't work fine with my Wacom pen tablet. And at that cost, it only warrants one look. Can't get their website to work in Safari. Wouldn't trust them to handle force-touch.
They say the best drum plugin is the one you carry with you. Like with cameras, it's about ease of use and the quality of the experience. So Microtonic takes the crown, for still being around, for being actively maintained, for PO-32, for Patternarium, for Sonic Charge also having made Synplant (♥). I'm exhausted and kind of sad to have blown money and/or time on things I ended up not using because of broken promises.
Should have bought Microtonic.