I am going to be little direct help.
I have had iPhone and Android...
My PCs are Win and Linux....
What I have found matters most is if the device works with my thinking.
So, plan a day, go to the stores and play with what they have. Talk to all your friends and see what you can get some hands on time with.
Don't Rush and Don't even consider the initial cost. (If you get the wrong one, the cost will be immaterial.)
Current phone is a Droid 4 because I have fat fingers and like a real keyboard.
As to data usage: If you only run the phone and are at home much of the time where you can run with house Wifi, 2G should be plenty. But, If you are traveling and tethering to a real computer, I can burn a Gig a week and sometimes more.
Matt