Has anyone tried using software drum machines or synths? If so, are there any you'd recommend?
Reason is a well known one. Ableton Live has a number of facilities for loop-making and so do the main DAW's and most DAW programmes will accept external plug ins like BFD 2 and the like for realistic drum sounds. Garvin recently switched me onto an incredible bit of software called Superior 2.:
But these are 'realistic' samples. Reason and Ableton are the simplest two for non-realism. If you want to get absolute control over every single possible parameter, Max/MSP is your friend, but that takes literally months to learn how to do what you want to do. It is incredible though. In theory Max/MSP can run CNC machines, lighting rigs... MIDI files, MIDI I/O devices AND process audio in almost any way you want to. That's what my last example was written in - and that's just very simple.