I will second Barbarian. A league I used to ring announce for always brought him in and he never failed to come up and shake my hand and ask me how I was, and then ask me how my family (who he has never met) were doing. Just a super nice man all around.
I've never met him personally, but all of the guys I talk too at the shows say that Bobby Eaton may be the single nicest human being on the planet.
While he is a bit scatter brained at times, The Maestro is a super cool dude. Always asks how your doing and goes out of his way to make you laugh.
Jim Duggan was a very nice man when I met him, had a smile for everyone in the huge line of people that were there to meet him, especially the children. Constantly letting out a HOOOOOOOO much to the delight of everyone in attendance.
Other guys who I've had experiences with that I would say rank them above the others guy's I've met: Tommy Dreamer, Brian Lee, Johnny Gargano, and Nikita Koloff
Also a special shout out to Chance Prophet. While he is not a huge name, and I actually knew him before he got in the business, he is legit one of the nicest people I have ever met in my life, in or out of the wrestling business.