Like Sarah, I can't speak for everyone, but my opinion is the best.
The first 3 Muppet movies are the greatest. They were Jim Henson films. That's pretty much agreed.
I personally liked Muppet Christmas Carol and Muppet Treasure Island quite a bit. Most people are iffy about these two. It's hit and miss.
Muppets from Space was a debacle, only because there was no original music. The story was ok. The cameos are now really dated (especially the "Hollywood Hogan" one.) And they ruined one of the greastest mysteries in Muppetdom... what is Gonzo?
A Very Merry Muppet Christmas -- I again enjoyed this one. No, there wasn't any music, but it was a made for tv movie, and most don't. I didn't walk in expecting it to have great music. The story was good. Lots of good references to other Christmas movies. Whoopi as God was.... uummmmmmm... interesting. But it seemed like they got back to the muppets roots with strange interaction between humans and puppets in an ordinary type of way. And Pepe stole the show.
Here's the scorecard as far as movies:
First 3: Everyone agrees (pretty much), 5 stars *****
Next 3: Disagreement between everyone, between 1 star and 4 stars */****
Last 1: More or less better reviews, 2.5 - 4.5 stars **1/2 / ****1/2
Hope that helps and have a nice day.
(Sorry for stealing the catchphrase Count.)