Current sim only contracts over here in the UK are amazingly good value. I just signed the other half up for a 12month sim only on 3, for £10pm she gets 300mins, 3000 texts, 1GB data and I got £120 cashback, a steal at that price!
The mid ranged Android phones are much of a muchness, I'm not a huge Android fan, if i had to leave my iPhone it'd be to a Lumia 800 Win Phone, but the One-X and Galaxy S3 have been making be really think about switching!