I've been using Guru for more than a year now. Working in Live, I use it in all of my tracks. I have Kontakt 4, and sometimes use that for percussion fills, but for sheer ease of workflow in setting up initial beats, nothing I've used matches Guru. Live has drum racks, which can do what Guru does in terms of sound manipulation, but the step sequencer in Guru is just fantastic, particularly the way you can tweak velocity, panning, cutoff, timing, etc with very simple graphs. Yes, Live does have nice automation, but it takes a good but more steps, and more tweaking, to get from Live what Guru will give you in about 30 seconds.
I've not tried BPM, but that looks like a Guru clone at best. Maschine has its merits just based on the controller (which looks nice) and the sample set (NI don't slouch on samples) but I've not seen anything that makes me think it is capable of doing more than what Guru already does. They talk about adding MPC-style editing in their 1.5 update, but IMHO Guru has always been as powerful as an MPC running on your desktop (up to and including most of what the MPC-5000 can do).