I use ebuyer loads, especially since they gave us a massive credit rating and  a nice account manager to tend to all my needs.  I can even get her on MSN if I need to.   Service is a little patchy, but they are cheap and do try and sort things out.  I've had a few faulty and incorrect items sent and they have swapped them no trouble at all, in usually within 7 - 10 days.
I agree with Ozzy about OCuK.  They don't even answer the phone.....ever.
They lost the chance of an order in excess of £100k from me.  How could I trust them to deliver if I couldn't even contact them.
Dabs have been okay for me, and I've never had a problem with Aria or Scan.