So you want to be one of the “in crowd”, and you’ve decided to shell out for a “jesus phone”, but now 02’s exclusivity agreement with Apple for the iPhone is over, you have the option of which network to choose.
Currently, both 02 and Orange offer the phone, with Vodaphone  getting it  next year. If you’re too impatient to wait for even more competition (as I was, stumping for 02 rather than waiting for Orange to get the phone), then your choice has to be made between 02 and Orange.
Lovemoney.com has a side-by-side comparison of the tariff options and handset costs, which are on the whole pretty similar between the 2 networks.
However, the article reckons that Orange is a slightly better option, due to its better network coverage (I’d concur with that, having a phone on both Orange and 02), as well as being able to purchase more texts as part of their bundle – handy if you’re a heavy texter, but with the iPhone’s internet capabilities, you may want to start using email more.
One plus on the o2 contract is that picture messages are counted as 4 Â texts, but come out of your monthly allowance, whereas I believe they’re charged seperately by Orange.
Both networks also have their “fluffy” benefits – the extra stuff they add on that aren’t really to do with the product you’ve purchased but are done to make you feel warmth towards the brand – such as Orange Wednesday’s or O2’s Priority service. For most people these features are probably neither here nor there when you’re paying £30+ per month on a phone such as this.
One other point made is that the customer service you receive varies between networks – the general consensus seems to suggest that 02  is better than Orange in this respect – but you’ll probably only experience this if you start to have a problem with your phone or the contract.
As mentioned above, Vodaphone will also be getting the phone next year, but the chances are that the tariffs will once again be similar to those on o2 – Orange had the chance to undercut o2 when they got the phone, but Apple may still be exercising their control over the pricing, and I wouldn’t expect that to change with Vodaphone.