I don't know, I think Palisades did a great job of Muppets they did include really, so it's really hard to list whom I really would of like. But I guess I'll if I were to go with a few (this list is in no real order by the way)...
1) Spamela Hamderson-I know their probably wasn't much to the character, but let's be honest, she was a beauty,
, so I think if done right she could of made just a amazing looking figure. Plus who won't want more Muppet pigs to add to their collection, along with more female power.
2) Sal-For reasons everyone here already mention
3) Manna Manna and the Snowths-Just cause, well cause their cool,
, well at least we got those mini figures of these characters, which were nice looking.
4) Here's a funny thought, but since some of the bigger monster Muppets were known for eating some of the smaller lesser known Muppets, what if there was a two pack of a big monster with a little Muppet, it could eat,
. Maybe Behemoth along with Shakey Sanchez, in honor of the "Under my Skin" skit from the Vincent Price episode of the Muppet Show.
As for characters already made, I do think they could of done a better more "eye-catching" Miss. Piggy, the best one might of been the first mate Piggy with the Pigs in Space playset. It's just my opinion that Miss. Piggy is the one Muppet that didn't do true justice for, I think the other muppets had really nice likeness minus our beloved Piggy.
Plus to go all out, I still feel sad when I think of the cancelled Sesame Street figures. Esp since series one was going to have Oscar the Grouch, whom is my favorite SS character, the Count would of been awesome too.