State your choice!

FL: http://www.fruityloops.com/

Ableton: http://www.ableton.com/live

Propellerhead: http://www.propellerheads.se/products/reason/

(My Personal Favorite.)Magix Music Maker: http://www.magix.com/uk/music-maker/?partnerid=9009&AffiliateID=2&et_cid=6&et_lid=661742&et_sub=uk_mgx_main_202clc_NAME

FL Studio 8. Because I find it very damn simple but yet giving me everything to work with and the ability to do really everything I want to. And because I started with it.

FL Studio 8, also.
I'm pretty sure most people favour FL. It's just near-on perfect.

My thoughts exactly, even thought I started with Magix Music Maker, it was a good program but a Basic edition. Limitation to Mixing and so on. And only 200 soundloops.

I've started making music with FL 8 Producer Edition now, it's not that simple for me, bu there are loads of things you can do in it. Piano soundloops, piano roll(high or low notes.)

Playlist and so on.

Quote from Überschall

FL Studio 8. Because I find it very damn simple but yet giving me everything to work with and the ability to do really everything I want to. And because I started with it.

Same here.