Best UK PAYG tariff

[Guest J273]

what would you guys say was the best uk payg tariff,Ive been with orange for ages and have just had me four o2 sims through and am thinking of switching to o2,Ive noticed it says that you have to topup a minimum of £10 per month is that for the credit or just the text and gprs,So if i dont topup in 2 months will my credit still be there or wil it of expired like vodafone used to do,Thanks