I haven't watched Punk'd, and only watched part of an episode of Wildboyz. (I like Chris Pontius, but Steve-O is best experienced in small doses.)
Viva La Bam, on the other hand, is right up my alley. Part of the joy of the show is that it's filmed right here in West Chester -- my sister was in the same class as Bam's younger brother, and you get to play "spot the local landmark" in most of the stunts Bam's ever done (both on Jackass and on VLB).
Now, Jackass combined a lot of elements. Steve-O and Danger Ehren specialized in sheer masochism; their appearances were of the "Hey, watch me abuse my body in strange and dangerous ways" variety. Pontius was more into Candid Camera-style stunts, generally flashing people in creative ways and catching their reactions. Knoxville did a little of everything, basically being a Hollywood stuntman gone horribly wrong.
Bam and his crew, on the other hand, were more like the local skate punks looking to get into some creative mayhem. (That's probably because that's exactly what they are.) Some of the stunts they've pulled are exactly the kinds of things people I know would've done in high school and college, had they thought of them at the time, which makes them more humorous to me than, let's say, Steve-O stuffing minnows up his ass.
It also helps that Bam's parents (particularly his father) have a sense of humor about Bam's antics. They seem like very cool people, the kind that I'd love to have as neighbors, other than that their son would be wreaking havoc next door on a regular basis. Heh -- maybe I should look for a house in Thornton.
It's an acquired taste. Maybe it helps to be in that 18-to-35 male demographic, as I am.