I think Dantley was the better player (than Aguirre, not Thomas), but didn't fit in as well from a basketball or chemistry (as the documentary showed) standpoint.
Dantley, despite his size, was an amazing post player. He was very creative inside and at times was nearly unstoppable. We would put McHale on him and he would go to work on him too.
Still remember him and Microwave colliding heads on a loose ball in the 4Q of game 7 of the 87 ECF. Dantley was taken to a hospital and Johnson sat on the bench loopy eyed with an icebag on his head. We might not have won if it weren't for that.
I know that I'm not of the demographic you're for, but I think that Aguirre was better for the Pistons, because of his willingness to see his minutes drop for greater team success, and because he was a much better shooter, with better range, than Dantley. When Detroit had AD, their half court offense would be very stagnant, but it was much more wide open with Aguirre, imho. Dantley was incredibly unique, though. Did you know that he had to wear a special shoe because one of his legs was longer than the other? I can't remember where I read that, but it's true. When he was successful against McHale it was probably mostly due to Kevin's foot fracture and ankle sprain, honestly, because by the time of that ecf, it was beyond recovery.
The only other thing that I'm going to say is that Dantley was one of Red's favorites, because of the DC connection I believe, and Auerbach even tried to persuade the front office to sign Dantley for the 1990-91 season, the year after AD had missed the final 37 games of the 89-90 season due to a broken right fibula. Ouch. I wonder how he would have fit in on that 90-91 team. Certainly his ability to get to the line would have helped tremendously, and he always got Scottie Pippen in foul trouble. If nothing else, giving Dantley the chance to stick it to Isiah and end Detroit's run in the 1991 playoffs would have been awesome. Even at 35, he was still much better than Gamble, who didn't do squat in the postseason that year.
Like Eddie20 said, he was an amazing post player, and he wasn't even 6'5". I think that there was a segment on some show that named him and Barkley as two of the players we'd never see again, and for good reason. Watching that piece, though, it shows that he was much more interested in having things his way, instead of sacrificing for the good of the team - kind of like where Kobe is right now, although Dantley wasn't even close to being any bit of the jerk that Bryant is. He was just a mystery to everyone. Here -
http://www.nba.com/history/players/dantley_bio.html