There are many online bookmakers. See our thoughts on them. All are reputable and safe so no ratings as such. We just go with the bookmaker with the best odds or offers. At the time of writing (January 2015) our favourite bookies are Bet Victor, Bet365, William Hill, Ladbrokes, SkyBet, Betway and Paddypower. We have accounts with all the bookmakers on oddschecker to make sure we always get the best odds. In the long run, the difference between 2.00 and 2.10 is huge so its worth shopping around.
The main things to look out for are odds, markets offered, on going offers and sign up bonuses. Sign up bonuses aren't that important because in the long run, they pale in to insignificance. Its the odds that really matter.
If you are really going to bet for a living, Betfair Exchange is the only way to go. They never ban winning accounts but they will tax you (call Betfair Premium Charge). Unfortunately, I've never even come close to it but this fellow has. Once you have made over £250k, you have to pay 60% of your winnings to Betfair.
Anyway, here are our thoughts on various bookmakers and their offers.