Well my 5 in no particular order -
Hulk Hogan: He put professional wrestling very much in the public consciousness with Wrestlemania. He helped the sport reached heights of stardom. Was a face for many years until he went to WCW and went heel with the NWO. Only solid in the ring at best but the guy had charisma in spades and knew how to work a crowd. Had a nice long career.
Brett Hart: I can remember him as a heel with The Hart Foundation as a tag team wrestler when I was growing up, but he was one of the few WWF (as it then was) starts who had good technical moves in the ring. Was convincing when he went face and showed he was good wrestler in the ring. Always impressed me. Injury stopped him whilst he still had plenty to offer.
The Rock: His ability to sell a feud, work the crowd, and his work behind the mike I enjoyed. In ring he was solid but nothing special but could work a fight without appearing lazy.
Ric Flair: Growing up, like many I had never seen any NWA?WCW events. However first bout I saw of this guy was a 2/3 falls match vs Ricky" the Dragon" Steamboat at Clash of Champions VI in 1989. It went just shy of 60 minutes and was all out. None of the "both wrestlers clothesline each other and lay on the canvass for a breather" this was full on and all the go. Flair was the heel to Steamboat's face but man it was one of the best bouts I've ever seen. Flair showed he could be a great technician in the ring, he had stamina, he had actual wrestling moves, he could work a crowd be it as a face or a heel (remember "The Four Horseman"?) and his promos? Man if you thought Randy Savage sounded "out there" at times, Flair made him seem laid back by comparison. He could work well behind a mike. Considering he wrestled pretty much from 1972 to 2008 I think you can say he had longevity.
Sting: This guy was one of the best in ring workers I've seen. Could be a pure technical wrestler, whilst also had the athleticisim to make some high risk moves. Could work behind a mike really well, and new how to work a crowd. Could more than hold up his end in a match. Also when you consider he spent most of his time either in the NWA/WCW or in independent circuits, it says something about how good he is that he is as well know as he is, and has an in ring career spanning 30 years. His adoption of "The Crow" inspire motif really gave him an extra edge promotionally in my book. Some of his matches against Ric Flair during the late 80s/early 90s were indeed epic. Also the guy is tough. He wrestled with 3 cracked ribs and ruptured spleen against Big Van Vader which says the guy was physically tough.
