I'm a character agnostic. I don't stick with one and play 90% of matches with him, I play the field, and as such I have formulated some general opinions. This is not top 5, this requires saying what you think I'd rather not focus on specific characters ITT, though I'd love suggestions on how to use characters that I can't use.
Bowser: He seems a lot stronger than Melee. The change in the side B move is great and he seems far more usable in general.
Capn Falcon: Unfortunately, I can't use him in Brawl. I was pretty decent with him in melee but in brawl something changed to make him much harder to use
Diddy: I don't get his specials. The popgun is too slow to be spammed but too weak to be precisely used. The Side B just seems weak and mostly useless to me. Bananas suck. That said, I seem to find him quick and annoying when I just stick to his non-specials. Though he doesn't have the best smashes, he can usually dodge enough to get them higher than 100%
DK: Aside from a truly pathetic FS, he's not too bad. His up tilt seems quite good to me.
Fox and Falco: fuck them
Ganon: Like falcon, I can't use him anymore. Sadface
Ice Climbers: Seem the same as melee but I've seen some crazy Nana antics where nana attacks and Popo isn't anywhere close
Ike: Dwight D Eisenhower was a truly great president, probably the last great republican. We like Ike!
Jiggly: Oh god the puff sucks. Sucks SO hard. The only saving grace is rollout Rollout spam is still crazy annoying.
Dedededede: A character that I just can't use well for some reason. Some people can though due to his powerful as hell smashes. One thing I do like is the range on his Inhale. I can't figure out how to work Jet Hammer.
Kirby: Still seems weak to me :/ I don't see any really good finishers.
Link: Outperformed by toon link, sadly
Lucario: Something about Luca is great to play as. Double team is a lot more fun than counter, but the long cooldown if missed is a drag. The aura-ness also makes him excellent against characters like meta knight who have a hard time finishing him off.
Lucas: I have no idea why but I find him SO much more fun to play than Ness (in brawl or melee at least, I loved ness in 64). I'm not especially good at him and when I mess up that light weight gets in my way, but I still find him fun.
Luigi: I haven't played that much as him in Brawl but I love his FS lol. The hitbox for the power up+b seems reduced, which sucks, and the low traction gets on my nerves. I need to play him more >_>
Mario: Can go fuck himself. I haven't barely seen him used or barely used him myself.
Marth: Since ike is in town, I haven't really been using him tbh, so no comment
Meta Knight: The insane speed he has and ability to find a way to hurt his opponent in almost any situation makes him a clear winner in my books.
Mr Game and Watch: Seems buffed from Melee, the down air is pretty strong now and his recovery is now really fantastic. His specials aside from up, of course, suck. Is more fun and still kinda wacky.
Ness: Lucas has taken my playing time for this duo, so I haven't really messed with Ness.
Olimar: This guy can be such a nuisance. If he lands a white pikmin on you, the damage adds up pretty damn fast. He seems like he has a lot of untapped power that somebody who can micro the pikmin well and adjust on the spot depending which is the leader can utilize. I am not that person, though.
Peach: Down smash nerf ftw. Can still be a nuisance but nothing I worry about. I also don't really play her much. Her FS is pretty nuts
Pikachu: This damn rat is a dirty, rotten whore now. Maybe it's just the different pace but he was tolerable in melee but as annoying as 64 in brawl. I don't really care to play as him.
Pit: My homeboy. If anybody could be considered my main, it would be Pit. From the insane recovery (as long as you dodge attacks lol) to the arrows to the spinning blades, I wuv him. It's not especially easy to get that killing blow but you can usually survive and dodge long enough to make sure you'll get there. Fun fact that nobody suspects: in a sudden death, a charged arrow wins.
Pokemans Trainer: Fun to play. All 3 pokemon have good uses, with squirtle's amazing quickness and withdraw invincibility, ivysaur's amazing range and overpowered bullet seed, and charizard's smashes from hell you can have a pokemon for every situation. As long as you keep range while you change, you can keep great variance in your attacks to be a good opportunist.
ROB: I just can't use this guy. He has some cool stuff but I have such trouble with him.
Samus: Projectile power, as always. As long as you play keep away, samus can harass with the best of them. Not nearly as bad as a lot of people think
ZSS: The Blue Sheik. Moves very fast, though I haven't been able to get used to her. Probably partially because I never remember to use her >_>
Snake: Sooooo fucking fun to play on certain stages. He is probably the most stage dependent character in the game. Planting his bombs, using his up smash, everything makes him amazing at setting traps. If you can predict the flow of the game and know where people will be, you can snake it up. On the other hand, I can't get grenade timing right and I can't quite detonate the C4 exactly when I want yet.
Sonic: People either love him or hate him. His signature moves dissapointed me (down and side special) but those are totally made up for the neutral B homing attack. It's so spammable and so opportunist it's great. Though as people play more they will learn to counter it, at the moment it just frustrates the shit out of most people. For that reason alone, I love sonic, even though his high speed is hard to control and his roll moves aren't all that. The awesome up special is also quite nice. If only he wasn't so light and he had a better finisher. I also like is down air attack.
Toon Link: Link but lighter and stronger means I have trouble surviving. Despite his major projectiles, I've mostly been an up close link and this makes Toon Link hard for me to play. Any pointers, or just general evasion?
Wario: Seems severely underestimated by everyone, including me. His aerials are unreal and chomp is annoying. His disjointed attacks make him somewhat unpredictable and make him seem faster than he is, similar to game and watch. I might want to play him more, actually. His FS is freaking great lol
Wolf: I hate the furries but for some reason find him fun to play. His attacks (specifically side smash) have momentum, making him a bit of a harder target to hit and makes it easier to pursue his enemies in. In a 4 player FFA he is a blast.
Yoshi: I just want somebody to break him
Zelda/Shiek: Rather than Melee, where they were only supposed to compliment each other, this time they actually do. Using shiek against fast characters and zelda against large ones, or using shiek at low percentages and zelda at high ones, you can actually have the variety to always be able to counter your foes. Particularly worth noting is Zelda's nayru's love buff, as a reflector it is actually usable now.
So what are your thoughts on mine? Am I a fool? A genius? How can I improve?