I think I would look around for a used metropolis - quite easy to use, very hands on and a lot cheaper than the usta
would you want too use CVTools with ableton? if so you could get an expert sleepers es8 or es9 and bypass midi and have an audio interface built in
it's difficult recommending sequencers as they are quite personal - what works for me probably won't work for you - and a lot of people construct sequencers from other modules, or use multiple sequencers (and other modules) together to form a much more powerful sequencer
"some of the best base-level info to remember can be found in Jim's sigfile" @Lugia
Utility modules are the dull polish that makes the shiny modules actually shine!!!
sound sources < sound modifiers < modulation sources < utilities