I'm going to buy an iPhone 4S: What network should I buy with?

Right then, following on from my rather lukewarm experience at the Three store this morning, I am looking to buy an iPhone 4S — on contract. Half of me thinks, ‘wait and buy it outright in November,’ — the other half says do it, do it, do it today.

Normally Three is my default provider for smartphone style services. I wanted an iPad from them but they were diabolically slow with me and didn’t take any flipping hints at all — so I bought one from Vodafone in stead. I do really like Three’s price plans and their unlimited data offering for their smartphones. However I don’t quite feel like doing business with them at the moment.

Therefore I’d welcome your suggestions.

Who should I get my new iPhone 4S from?

My primary provider is Vodafone. That’s what my BlackBerry 9900 runs on. My wife has an iPhone 4 on Vodafone. I’ve got about 4 other accounts with Vodafone. If they offered me a two-for-one (unlikely, but, you know) for myself and my wife, I’d probably buy 2x iPhone 4S devices from them.

Or perhaps I should be looking at Orange? Or o2? In fact I’ve got a free o2 line that’s due an upgrade. Or maybe I should — finally — revisit T-Mobile and give them the business?

What do you think?