beside the people with whom i've been lucky enough to play, here's my list (or at least part of a list).
when i started to think about this list, i noticed that most of these people were in the improviser/composer/visionary zone:
coltrane
miles
wayne shorter (miles and blue note eras)
bill evans
eric dolphy
john mclaughlin (earlier)
anthony braxton
lester bowie
mark dresser
dave holland
to be honest, having favorites is sort of funny - - there are so many people from whom i learn when listening to their improvs, even the ones i dislike may teach me just as much as the the people named above. i guess the deciding factor that all of the people above share is that i keep going back to them and that their work produced a sea change in my own musical voyage - - of course these are only the people who do improv and represent a "current" list, it could change tmorrow . . .
addtionally, there three people who i've only heard about being amazing improvisers, but whose music has meant a lot to me, that i wish i could have heard improvising:
bach
mozart
beethoven
stig