I think the choices have been decent so far. Probably in order from worst to best for me would be:
Mii: Not a particular fan of using them in any game, but was not surprised at all by their appearance.
WFT: I get it, it's the unexpected character, but this one is more objectionable to me than R.O.B. ever was for some reason. This said, I don't dislike her, but I certainly won't miss her if she does not return in the future.
Palutena: I am ambivalent on the character as I have not played Uprising. More than anything I dislike her implementation regarding custom moves.
Villager: Nothing against the character, but he is not one which generates any hype for me and he doesn't seem to be a character I'd enjoy playing as.
Little Mac: Honestly for me this was one of the more surprising reveals, Punch Out doesn't seem to be anywhere near as big in the UK as it apparently is in the US. A cool character though who seems to be enjoyable to play as.
Greninja: This is where the hype starts. It was an unexpected addition but a great one in my opinion, and (even though it wasn't intended to be) is nice for the competitive Pokemon community, where it is very popular.
Rosalina & Luma: Personally a big fan of both the characters and their implementation/gameplay style. Likely to be one of the characters I use the most when the game releases.
Pac-Man & Mega-Man: These two are together because a lot of the hype is them being together along with Sonic and Mario. In my opinion they are easily the best 3rd party choices for the game, and I'm glad they're in. If I had to choose between the two though, I would probably choose Mega Man as the most hype-worthy, because of a few reasons: he was not as predictable as Pac Man (With Bamco helping develop, it seemed inevitable anyway), his moveset is pretty much perfect in my opinion and I also get the impression that Mega Man as a character seems targeted more towards core Smash players, whereas Pac-Man has substantially more appeal to a more general crowd.