I wanted Banjo so badly, but there's just something about him that feels overwhelmingly meh. I think it's that he doesn't have a very free-flowing combo game, nor a lot of damage and power on his moves. Just about every other character is strong in at least one of those departments. And then there are the smaller issues, like how up tilt would be one of his few good kill moves, but it lacks a scooping hitbox which heavily hinders its utility. His down throw is probably the weakest bury in the game, so you're waiting till very late % to do much with it. And WonderWing is, quite frankly, kinda bad. I get the sense that he's so undertuned because WW was supposed to be his big wow factor, but in its current state, I don't think it makes up for Banjo's shortcomings. The armor is nice, but it has slow startup, a laggy animation if you miss, loses to grab, and the sweetspot is only out for a short duration. Sometimes I've been pretty sure I hit the sweetspot, only to realize I actually didn't. The sourspot kills very, very late. Banjo also lacks shield safety on most of his moves, and even struggles a little to play the projectile zoner role, as his projectiles, while they're solid enough, just don't open up the myriad of possibilities as, say, the Links' or Duck Hunt's do.
I really hope they focus on buffing Banjo in this upcoming patch. As more and more characters get QoL love, Banjo starts to standout as a character who could really use it. He kinda feels like a better pre-buffs K Rool to me, when K Rool felt so much better and finally felt satisfying to play as upon receiving his first round of buffs in the patch that added Terry. Just feels like Banjo needs that same love now.