@Glowsquid, you've asked to me to share my thoughts about Mega Man 6 once I get to it and I just beat it so here I am.
I totally see how it could be your favorite to be honest, the level design is really good in this game, it has a satisfying balance of difficulty, especially in the castles stages. Actually, it's the only castle stages in the series I really like so far. The levels look amazing for the NES, which is not surprising since this their sixth game on the hardware but still. The music as just as good as the other games, which is great. Not my favorite soundtrack in the franchise (that would go to MM2 or 3) but still very good. The thing I like the most about the game is how they decided to handle Rush. Making it so fusions with Mega Man is a lot better then just using him as item. The level design does a lot of cool things with that, I love the alternate paths they provide.
There are only 2 things I dislike about the game. Something that is kinda minor is the Robot Master design, I'm not the biggest fan of them. I like Tomahawk Man and maybe one or two others but the rest is kinda weird to me compared to the other games. Especially, Centaur Man, I just think he looks weird, not a fan of chimeras in general. That's kinda picky of me, I know but the RMs are like on of the most iconic part of a Mega Man game for me... Guess they put all the cool designs in X1.
The second one is the slide glitch, it's really noticeable at first, especially right after playing MM5. You get used to it but it does hinder my experience a bit. I think there's a patch for it but I wanted to play the original version first. Next time, I'll just use the patch. I wonder how that slipped through game testing. Was this game rushed too? Does it have anything to do with X1 releasing the same year?
Anyways, I don't know if it's my favorite classic Mega Man game for now but it's the definitely one of the better ones. I think it's better than 5 and though it may be considered objectively than 2 or 3. I'd see myself replay them more. I like more than 4 and 1 though. I'll be glad to hear your thoughts (or anyone else having playing this game) about it. I'm not too familiar with the Mega Man community and the common consensus for this game (or any other except for maybe vaguely the first three).