I've had pretty good luck with CG so far, but it's just that - luck. Obviously, sets with more good cards are going to be generally seen as better since you have a better chance of getting something that doesn't blow. CG has a lot of good cards and great Pokémon-ex; Emerald, on the other hand, has a couple good Pokémon-ex and the rest is garbage except for the Trainers.
Of course, what's "good" and "bad" in terms of cards is in the eye of the beholder.