I would prefer FL studio above Sony Acid Pro, but the best programme for music creating is Steinberg Cubase 5 in my opinion.
Because many DJ's from the Netherlands (yeah I am from the Netherlands) are using that programme to make their own housemusic. It's harder to big good at than FL studio, but if you understand the programme very well, you can figure out it has got more functions than FL studios. Mayby it's better for you to start with FL studio if you aint got mutch experience with any music creating programme, but still I would try to work with Cubase.
Hope that I informed you enough.
Nice nice if you want to help me to use the programme, please help me. I would love to learn that too =). FL is also a nice music creator programme. I think it's a bit easier to understand.