My personal recommendation is
Mecca Bingo - that's been my favourite. The general theme is to go with the big brands, some of the smaller offerings how some questionable terms and conditions. At Mecca the prize money and value are superb.
Littlwoods and
Castle are not far behind, and if you look in the offers section, you can get
bonus codes for when you sign up.
Avoid anything from the Globalcom network!
I need to try Gala, but I'm having troubles depositing with them as I had an old Coral account and they've mashed up all the details - I need to get that sorted.