I had an Alesis HR-16(A). It was okay but nothing exciting. I also had a Boss DR-550 mkII which had some good samples, but the timing over MIDI was atrocious. If I wanted a usable steady kick, I had to move all the other sounds back or ahead a few ticks off the kick. Not a limitation I would have desired, but in a roundabout way, it did teach me some of the benefit of not having everything on the grid. I don't have any drum machines now. I moved everything to samplers a few years ago (first hardware, then software) and I haven't looked back. After years of being stuck with the same old sounds that I had with those two units plus a couple of ROMplers, I now prefer to either synthesize my own drum sounds, or take mundane samples and mangle them into something entirely new. Having said that, I've always had a fondness for the chirpings of the CR-78, though I've never used a real one. Likewise, somehow I'm still not quite sick of the TR-808 yet either, but it's simply not worth to me what it goes for nowadays.