Originally Posted by Mockery
Ableton Live is all I use on my PC and I absolutely love it, and yes, it is available on the Mac too. Get it :o
YES. Once you go Ableton you never go back. I used Logic for a long time on Mac and before that Cubase on PC, but nothing compares to how intuitive and just plain fun Ableton is once you get into it. It was a bit of a learning curve for me because it's so different than traditional sequencers, but well worth it.
For Linux seq24 is a great MIDI-only sequencer - rock solid timing and totally geared for live use. I was unimpressed with the rest of the Linux offerings, not to mention the massive headache and time involved getting any of it to work properly. If I recall correctly, one of the big sequencers on Linux is Rosegarden, but I found it highly unstable.