There are several forums online that specialize in this area.
Watch how they react to client issues that come up and how quickly some solve it without insisting on opening a ticket. You can also get an idea as to who is reselling and who actually owns the server.
Stay far away from anyone who offers unlimited bandwidth and disk space. What they fail to disclose is this usually means unlimited slowness. Many of these hosts have no qualm with placing too many VM/VPS's on a single hardware host.