Welcome to the forums first of all & i hope that you enjoy stay here its a great forum and there is a lot of help on hand if you need!!!
First i would say you would have to answer some questions to choice the right iPad for you and this questions should help you make your mind
up which in buying
Do you watch a lot of films or Tv Series?
Do you like to surf the web on the move a lot?
Do you do a lot of reading?
If you like to watch lot of films or Tv Series then i would suggest getting a big captivity iPad so that you can store a nice big collection of videos of Tv Series
64GB Version to Store things mini or 9'7 iPad would do this its down to your personal preference.Personally i like the mini for reading and then i like the 9'7 iPad for watching films or Tv Series.The problem with Tv Series and films it can soon eat away at your storage and you soon wont have much left on your device if that what you are going to use it for.
If you like to surf the web a lot then i suggest either getting a data plan with a iPad so you able to surf the web at your leisure and you don't have to worry about wifi signal.(just keep a eye on your data if you go on this route because it can go quick depending on what plan you select)
If you just like to read books and just do some do some surfing now and again then i think a wifi iPad mini would be perfect for you because you wouldn't really need a connection if you are just reading books
Its all down to your lifestyle and what you do only you can really answer this question sorry to be blunt but its true you have decided what you are going to do what are you going to use the ipad For.
Me personally when i go out i like to go on facebook & twiiter and forums so i just tether with my iPhone 4s and that suite me fine
for how much mobile internet connection i need which isn't much.
I would go to the apple store first and try the mini out and the 9'7 iPad before getting one
I hope my information has helped you out and that you are happy with your purchase