All the networks do PAYG.
Choosing one is a matter of picking
- the tariff that suits - they all differ slightly. BUT: All networks charge less for calls to <landlines and other users of the same network> than for <calls to other networks>. So, if there is a predisposition within their circle of friends and famility towards a given network, it is economic sense to use the same one.
- coverage: some more rural areas are better covered by some than by others.
If neither of these are a factor, then I suggest Virgin is probably the best PAYG tariff. In fact, Virgin have exactly the same tariff for Pay Monthly too. More convenient, I'd say because you don't have to pre-pay nor remember to top up and you lose nothing if you go dormant.
Alternatively, I reckon Orange is pretty good for coverage in odd places.
More details on Virgin from
www.virginmobile.com