I'll keep the ball rolling here with a PD recommendation for Rarebeauty - she is.
PD has some very legit providers,and when it first started reviews were generally worthwhile, but now they are totally corrupted with guys who are understandably seeking a positive reply from the provider to their review so they canbe more easily verified by other providers. And it sure seems there are a lot of outright fake reviews, but I dont know that for a fact. All that said, there definitely are a few very negative reviews, albeit too rare for it likely there isn't some (lots?) of moderation/deletions.
If you read enough reviews there, you'll prob get a sense of who the truly bad providers are, but beyond that it is not very reliable. But there aren't really any other options out there yet, no?
Oh, and dont bother with the forum there - it is a complete buzz kill with a few omnipresent providers that seem to have a lot of time to harsh.