Technically speaking Kirby is one of the worst characters in the game, but still lots of fun due to being so unique. The character I do the best with is Mr. Game&Watch, which a lot of people have a hard time believing before kick their asses. =P
Tournament players have all kinds of tier lists, but they're mainly about how good a given character is at countering their ridiculous playing style in a no items, Fox-only, Final Destination environment.