IPhone 4 vs iPhone 4S vs iPhone 5? - 2

I want to get a smartphone and go Tmobile with it, so it would have to be unlocked or be bought off contract. I could buy a 32GB iPhone 4 (used but in good shape) for $100. But I could also buy a used iPhone 4S 16GB for around $200-250 or even an iPhone 5 used 16GB for around $300-350. I'm not sure which one to get, what should I do. Please keep costs in mind also. Also, please don't say get another phone because I have thought this out and these are my three top choices.

I would go with the iPhone 5 because it is the most up to date version and is a better phone.

Can ypu please anserr mine?