I think I've to weigh inn for Digiweb on this one. I've been with them for nearly two years now and find the service excellent. Very attentive on the phone, very good download, and pings.
The "rolling" 30 day quota system works fine for me as I check it regularly and keep it 80-90% full, getting nearly the most out of it.
ISP bashing in most cases is deserved - but I think that Digiweb are one of the few good ISP's. (Of course if this changes I'll be back to change this statement
)