Khali is a gimmick. The WWE loves it's giants though. Dude won't be around long. ECW has gone to the crapper. It started off tight, but they don't have enough of the old original ECW guys, and they focused way too much on raising its' popularity by bringing in RAW and Smackdown guys as guests. They haven't done enough promoting from within. They had their own McMahon in Paul Hayden/Haymen (?) and he did his job as antagonist well. The Big Show was doing good also. They since have steered away from those two, RVD is going to leave. Lashley was a good idea, the guy is a beast, but it may be too little too late. They also haven't had any good storylines developing lately. TNA isn't half bad, I'd say it's better than ECW is, right now anyway. Samoa Joe is a beast. He is real good. The feud between him and Angle was nice.
Generally with the shows, RAW is the best bet, IMO. Smackdown has a bit of a kiddie feel to it. All the shows have a decent match at first, then crappy filler, then the last couple matches are good. They can't all be great, and it seems like a good set-up.