I've purchased from Power Computing, Eyetech, KDH Datentechnik, Haage & Partner, and anoher one in the UK I can't remember (but it has an "A" in it somewhere)
Anyway, Eyetech were fantastic - gave me lots of advice, both by telephone and email, sent me wiring diagrams to help, even helped me sort out a problem with an Eyetech tower I had bought second hand on Ebay, and everything I have ordered from them arrived very quickly.
Unfortunately, they no longer sell Amiga hardware now (I think they do have some stock remaining though, but they're concentrating on selling PPC boards).
The next best was KDH Datentechnik - they took back a dodgy G-Rex board I'd purchased from them and let me use the money towards a mediator + mirage tower, which arrived very quickly (4 or 5 days iirc).
Power computing just gave me the general impression that they "Couldn't be arsed" any more with Amiga customers. Never replied to emails, took ages to answer the phone and when they did weren't of any help.