It depends on how much you are prepared to pay for your hotel. I stay at the Ambiance because I like being in the centre of the action.The best rooms are of reasonable quality and not that expensive. Copa's are nice too but that is more of an apartment block than a hotel.
However, next time we are also staying for a few days at The Agate in Jomtien. I looked at the hotel a few weeks ago and was most impressed. i was told that direct booking (as opposed to Agoda et al) gets you a better price.
Of course, another issue is whether you want a gay hotel.....Ambiance and Copa are certainly that!