I've used Renoise, Ableton, Reason, and FL Studio in the past. I've been using FL since I was 13 and messing with loops and drums, and I still use it because of how much I know it. I'm still learning stuff about it even now.
Reason is a synthesis brute. You can get some really nice sounds out of it. The sequencer is shit, though. I'll usually just rewire Reason's synths into FL.
Ableton Live is really prim and proper and has knobs that do everything. The macro feature was awesome when I used it. But it never really stuck with me like FL did. The whole process never really clicked.
Renoise was good, but I get tired of trackers quickly, and I'm a visual learner - if the automation clip says "make this knob turn up to 90% over three bars", FL shows that in a nice graphical format.
FL Studio does everything I need it to; the pros of it far outweigh the pros of any other DAW I've used. I just wish it had Reason's synths and Ableton's automation features.