With protein skimmers you get what you pay for.
The list of skimmers to avoid is too long to list... nobody understands how good a good skimmer is until they see it in action and realize what they've been "tolerating" all along.
It's easier to list good skimmers (as the list is far shorter).
Good skimmer brands include AquaC, MRC, Euro Reef, Deltec, Bubble King, Octopus, ETSS, and others.
Another approach is to look at skimmer technologies. Downdraft, Beckett, Induction, and recirculating skimmers will always triumph over ventiuri, single pass, or airstone designs.