Four very different shows.
Impact - I don't follow TNA wrestling although I am aware of some of it's goings on. From what I have occasionally seen of the show, it isn't great. Sure, if you want an 'edgier' product then this is the one. But to me, it isn't up to scratch. The booking is off, for example, why did AJ Styles drop the title to RVD and not even keep a feud going. However, a redeeming feature is the brilliance of Mr. Anderson. As I don't watch it, take this as an outsiders point of view.
NXT - I thought the first season was really good for a pioneering concept. It's going to produce some big stars for WWE like Wade Barrett and David Otunga. It had it's down sides like the challenges which I just felt (with the exception of some) were pretty boring. Season 2 is going to be better where they can perfect the formula for the show.
Raw - Very entertainment based. It's still good even if it doesn't focus on the wrestling side as much as other shows. The roster does give it an edge to some other shows. On what other program can you find Cena, Orton, Triple H, Edge, Sheamus and Jericho. A negative of Raw, is that it doesn't allow midcarders to shine. Take Ted DiBiase, you have a great young wrestler with a good gimmick who is being totally buried due to the amount of main event talent.
SmackDown - By far and away the best show right now. It's roster is a good mix of big names (Undertaker, Mysterio, CM Punk) and rising stars (Kingston, McIntyre, Swagger). The booking on it is also excellent. The Punk-Mysterio feud was an example of this. It had a good build, fantastic promos and an unexpected, spectacular ending. To me, that was an example of awesome booking.
There is a common misconception that the PG rating of WWE programming creates a worse product. Completely untrue. To make a great wrestling show, you don't need frequent blading and 'shock' factor. You need a good creative team, consistent booking and good wrestlers. WWE in the last few months has done that.