I am going to go out on a limb here and probably offend some people. My choice of the most boring entrance has to go to...*drum roll please*.... The Great Khali! I know, almost no SANE person was truly offended by that, but it's true. A few posts back, someone mentioned Andre` the Giant lumbering to the ring, but I must say that Khali is almost just as bad if not worse. There isn't even any pyro to distract us from the fact that the person coming to the ring sucks!
If it were me, I would have Khali ride down to the ring on a camel, that would suit him better than any other entrance that the WWE could POSSIBLY line up. Plus, since he is portrayed as this giant gibberish speaking Arab, it would fit his gimmick PERFECTLY!