No particular order.
Fox
Amazing ability to punish. One hit usually means several more, and around 50% of damage, especially at low percents. Also good at forcing the approach.
Marth
Basically like he his in vBrawl, but with combos that do a lot of damage, and Dancing Blade is never decayed by the time you get to KO percents.
MK
Soooooo good at gimping, and very difficult to approach. Can do two dairs in one short hop, which gives him a solid approach that's very difficult to counter.
TL
Incredibly good at spamming and comboing. Has near guaranteed combos into uair for KOs, and a pretty good edgeguard.
Falco
Lasers are still amazing. They are fast, unpunishable, and very good at frustrating approaches. Reflector is now dumb, as it perfectly compliments his lasers at a range where most characters can't punish even on block, and leads into all sorts of combo moves, to compliment his already crazy combo game. (I don't think his Reflector should have been changed. He's great without it.)
Diddy
Bananas are still incredibly good. They control space really well and lead to guaranteed punishment, which is now made more formidable with B+'s combo engine. Diddy's pretty amazing.
Kirby
Bair.
Snake
Ftilt.
Olimar
Grab game is stupid good now. Either he has massive guaranteed combos, or he has really easy tech chases.
Sheik/Zelda
Ace combos, incredible shield pressure game, crazy edgeguard game. Sheik is pretty much enough for most foes on her own, but Zelda can net some wild damage output and has crazy KO potential for her own part.
Luigi, Squirtle, Wario, ZSS and Falcon get honorable mentions for being really good, but my top ten definitely have it on them.
Fox
Amazing ability to punish. One hit usually means several more, and around 50% of damage, especially at low percents. Also good at forcing the approach.
Marth
Basically like he his in vBrawl, but with combos that do a lot of damage, and Dancing Blade is never decayed by the time you get to KO percents.
MK
Soooooo good at gimping, and very difficult to approach. Can do two dairs in one short hop, which gives him a solid approach that's very difficult to counter.
TL
Incredibly good at spamming and comboing. Has near guaranteed combos into uair for KOs, and a pretty good edgeguard.
Falco
Lasers are still amazing. They are fast, unpunishable, and very good at frustrating approaches. Reflector is now dumb, as it perfectly compliments his lasers at a range where most characters can't punish even on block, and leads into all sorts of combo moves, to compliment his already crazy combo game. (I don't think his Reflector should have been changed. He's great without it.)
Diddy
Bananas are still incredibly good. They control space really well and lead to guaranteed punishment, which is now made more formidable with B+'s combo engine. Diddy's pretty amazing.
Kirby
Bair.
Snake
Ftilt.
Olimar
Grab game is stupid good now. Either he has massive guaranteed combos, or he has really easy tech chases.
Sheik/Zelda
Ace combos, incredible shield pressure game, crazy edgeguard game. Sheik is pretty much enough for most foes on her own, but Zelda can net some wild damage output and has crazy KO potential for her own part.
Luigi, Squirtle, Wario, ZSS and Falcon get honorable mentions for being really good, but my top ten definitely have it on them.