Looking back on the times I always felt that WCW/NWA was just able to come up with better stables. Nothing against formerly the WWF, and currently WWE's old stables from the early 90's. However, we all know WCW had The 4 Horsemen, The Dangerous Alliance etc, but the WWE had some stars as well that I believe could have been just as solid as either of the ones from WCW that I mentioned. Granted The Horsemen had long established themselves, but the WWE(f) had a talent going at the time.
First let me start off with the first stable. Most stables at that time usually one had leader, but this stable could have broken that chain. Back in the 90's I always thought that the best heel stable could have been Curt Hennig, and Rick Rude as the possible tag team since they grew up together, and were both really good friends. The other two members would be the leader, and soon to be star Shawn Michaels with the muscle of the group being Sid Justice. In the early 90's HBK was just coming in to his own, and would have been the ideal leader for a stable like this.
Next, would have obviously been "The Kliq". I don't know why the WWE(f) never considered this at that time. HBK, HHH, Razor Ramon, and Diesel. With both men soon leaving for WCW it would have given them a reason to split. Whey they had shown up on WCW as The Outsiders, I would think that if they were part of a stable in the WWF at the time, this would have been an even bigger deal. Everyone, and their mother would have thought that HBK, and HHH would soon follow. The Kliq would have been the best stable of all time had they actually formed on television. I honestly think the WWE could have WCW out years before it did. Nash, and Hall along with Hogan really kept WCW alive in terms of the script they had with the NWO. It was a compelling story.