reason is the king of midi composition. you can rewire it into most wave studio software too.
something like Reason rewired to Abelton is immensely powerful
it does take a little while to work out reasons composer window, but once mastered it so easy and intuitive, you will feel like a fat kid at the end of a pie conveyor belt.
at SAE institute (school of audio engineering) the software that they teach you the trade on is Pro-tools,Reason and cubase
Protools is the industry standard, it is a reliable work horse and is extremely flexible, but is expensive.
we learned cubase for general home recording applications, I imagine by now they have replaced cubase with abelton, as abelton is more intuitive and simpler to understand and use, and has greater power than cubase.(cubases interface annoys me)
Reason has all the ease of digital midi and usb devices

it hooks together like real audio equipment, so even though it is virtual, you are still learning how to set up real audio gear. which is handy.
there are enough presets to satify novices, and enough flexibility for advanced users to go ape tweaking it out to perfection, or even build synthesizer sounds from the ground up.
the entire scope of reasons power is too great to really explain here, just understand that there is very little that reason cannot do with it, and rewired to abelton or protools, it is unstoppable.
if you have the doe then reason is the go
Sometimes I like to use words out of contents