I keep trying to figure out which mobile network would work best for me in London. I'm currently with Vodafone UK on a simple pay-as-you-go scheme - I just don't want to commit yet (I still regret ever signing on for my current plan back in Romania). However, I will have to upgrade eventually - and this time I plan on getting it right.

So I want to study the market. For starters, I ordered pay-as-you-go SIM cards from every major network (O2, Three, Orange, T-Mobile, Virgin Mobile). I plan on using each of them one week at a time, reviewing them here as I go along. Here are the main points I think would be worth discussing:

General Reliability
Voice (reception, in-call sound quality)
Data (3G coverage, speed)
Customer Service
Pricing

Once again, this wouldn't be a very in-depth analysis, but rather a simple study of what would work best for someone like me (smartphone user, always on the phone, often calling international numbers, moderate texter, heavy data traffic consumption).