I'll agree that kender aren't the problem, the players are. Even Tas shows character growth in the novels.
Gully dwarves are an inexplicably bad choice for a PC race. Too many disadvantages and ... wait do they even have an advantage? As NPCs, they're fine.
It depends on the edition too. I'd say half-orcs are the worst in 1e given the class restrictions on them. Get to 3e, and the worst of the core is half-elf playing the role of the poor man's human. A big step down from AD&D where they had a good deal of versatility from their multiclass options.
I'm not a fan of dragonborn either. As much as like to keep mocking the dragonboobs silliness from early 4e, the real problem is that WotC put too much background flavor into them. That's a running problem I have with WotC material, they put too much specific background stuff into things rather than leaving things open ended enough for a DM to customize things.
Optional races can be hit or miss. There's a lot of junk from 3e, and raptorans are near the top (Races of the Dragon was one of 3e's lowest point anyway). Most of the new stuff they made in 3e gets a meh from me at best, and only legacy material has much interest.