I have two distinct rankings for just the first movie and everything to come after; I have practically no thoughts on Ruby other than her being superfluous so I've left her out of the ranking.
For just the first movie:
1.) Ducky (yep yep yep!)
2.) Littlefoot
3.) Spike
4.) Cera (saying she's likeable in the first movie is a big reach but she's still a fun character)
5.) Petrie (I don't dislike him at all but I think he's unsuccessful as a comic relief)
...and the sequels:
1.) Littlefoot (at the top because he's the most consistently likeable of the main kids)
2.) Cera (though I have serious problems with the direction they took her in after IV, even after the character switch, I'd say she shines more than any other character; she and Littlefoot would be swapped if her portrayals in VIII and XI were remotely tolerable)
3.) Petrie (he's occasionally entertaining)
4.) Chomper (as much as I question the direction they took his character in in V and onward, I'll concede that he's pretty alright either way you slice him)
5.) Ducky (she's only this low because she barely does anything; when she gets the spotlight, she's hit-or-miss)
6.) Spike (the character I think consistently has it the worst in the sequels, he's a bland mouth with legs that's more often than not worse than useless; that said, he shines every once in a while, namely in VIII)
