This forum is really hard on Brian Leetch. I think, maybe, there's a recency-negative bias where people are remembering his latter half more than his first half.
In recent years, I've watched a few Rangers' games (and '96 World Cup) games from the early/mid-1990s, and there is no doubt that Leetch was the best player on those teams, and was the straw that stirred the drink (not Messier, not Lindros '96). Like, he was seriously good. He was the best player on the 1994 Cup champs. He was the best player on the 1996 World Cup champs.
From around 1990 to 1997, I honestly don't think there was a better Dman in the NHL than Leetch. Yes, I would take him over Chelios in that period, and also over Bourque -- they were both getting a bit older, while Lidstrom was still young.
Similar to Leetch, I could also make a case for peak-level Chris Pronger (or Chelios, maybe, though I'm not as high on him as most) to be in the top ten. But it's the prime vs. longevity thing. Leetch and Pronger didn't maintain their super-elite level as long as maybe we'd like to merit top-10 consideration.
So, ultimately, would I have Leetch in my top 10? Probably not, no. But if we're talking about prime level, then maybe, yes.