FL studio is good for beginners, also lots of instrumentals for popular songs are done on FL studio, but they are mostly hip hop instrumentals.
If you have a mac there is Logic/Logic pro which is apparently very easy to use.
Cakewalk sonar is also an option.
Steinberg Cubase is also a good program.
I use Reason 5, it has the look and feel of a rack of synths and mixers, you can get some very warm and deep sounds however I haven't touched it in quite a while.
Also Reason 5 doesn't support VST's but you could take that as a positive or negative.
Ableton is used a lot these days, don't know much about the program.
Best thing to do is to try a demo, most demos are free.