I'm surprised no one has said "Bam Bam" for old time. Former Bounty Hunter, Former bouncer, and I've personally seen him in more then a handful of biker brawls. (Also: hands-down the nicest person I had ever met in my life, so long as you weren't someone that pissed him off)
As for now, I've definitely heard plenty of stories on Taker and if even 1/2 of them are true, I certainly wouldn't want to mess with him.
i ll say taker, lesnar, booker and big show,
Dean Ambrose is not a trained wrestler, but he has poor mans street fighting is a freaking lunatic so it could account for something. TNA would have to be a Samoa Joe, but as a signed active performer Alberrrrto Del Rio..
Now outside of the USA Kenta Kobashi is the toughest!! He did Judo and Rugby prior to wrestling, and he is crazy stiff
William Regal is Boss!