M7 usually releases the recent Bleach chapters in 1-3 days and HQ, better than all other Bleach scanlators. I ONLY download Bleach from them.
While Japflap releases Naruto a week after the raw was released their releases are great quality and I don't mind waiting.
I try to stay away from groups that do too many series. Those groups usually end up dying 'cause of too much to scanlate. So I never try to depend on them. Null, for example. They use to do the Best One Piece scanlations, but since they do other stuff(and they are probably busy[scanlators and fansubbers have lives too]) they rarely release anything. Most One Piece scans are pretty shitty, but the shitty scans are the best we got.