In a stand up fight with all the people in their primes, I'd give the nod to Chuck Norris. He was a world champion, I believe. He also tangled with Bruce Lee, at least in a movie. He would've had just as much chance vs. Lee as Lee had vs. Chuck.
Segal is a wuss, Norris would've smoked him.
If you let all the fighters to fight no-holds-barred, I'd bet on Goldberg. None of the others would stand a chance after he tackled them, and remember, Goldberg is a legitimate athelete. He was an all America linebacker at UGA, I believe, and played pro ball.
Despite his size, Goldberg would be the fastest runner of the bunch, as I believe his 40yd time was around 4.5-4.6 secs. He wouldn't be the quickest, but the smaller guys wouldn't be able to run from him, and they would have absolutely no chance once he caught them.
All that crap about them standing back and taking Goldberg (or anyone else that is larger) down with one punch or kick is B.S. It would have to be one lucky, lucky blow, and they'd have only one chance. It's really irrelevant that what he does now is fake.
How about this: Put any of these people in a ring with a quality heavyweight like Tyson, Ali, etc, with gloves on and I say the boxer wins every time. Yes, even if the martial arts guys are allowed to kick.