Apologies if this has been said already, but I find the Korg Volca keys to be pretty bloody versatile. You need to run it through distortion or overdrive to get any kind of volume out of it for a live setting (or just whack up the gain on your mixer) but there's a good mix of sounds and settings so you'll never be short of different sounds to use. Same goes for the Volca beats for a drum machine. I only use it very sparsely, a couple of kicks per bar to give the set a bit of momentum but there's lots more you can do with it.
Arturia Micro Brute is great too. I've found it to be a little temperamental at times and it's real shortcoming is that it's monophonic, but there's a great range of sounds you can get out of it, especially nice thick low and mid frequencies.
