Coming from someone who's sole request was a new Kirby rep, be it Bandana Dee, Marx, Magolor, or Dark Matter, here's my perspective...
Spoilers ahead
I'm neutral for Banjo (I've only played one Rare game in DKC1) but I'm happy for all of their fans and would be eager to play as them.
I'm freaking psyched for Geno and Isaac. Actually looking forward to heavily. Those two get my happiness.
Chorus Kids? Not excited for in the least. I'd be okay with Karate Joe, but Chorus Kids themselves seems like another Ice Climbers without the nostalgia appeal and are on the level of Minecraft Steve in worthiness to me.
Ken and Shadow I'm okay with. They're perfect for echoes, and I'm happy for their fans, but they're still 3rd party. I like 3rd party editions, don't get me wrong, but the amount of 3rd parties from one franchise shouldn't approach the amount of reps from a mainline Nintendo franchise like Kirby.
Mach Rider, I have an interesting opinion on how I feel. See, nobody knows if Mach Rider is actually a male or female due to something in the game Vs. Mach Rider, and my excitement for Mach Rider changes depending on how Sakurai handles the gender. If Mach Rider is female, I'd be happy because one, another female Smasher is good and two, and most importantly, I can already see the fan comics happening between Mach Rider, Captain Falcon, and Samus. Heck, I can already see the meme with the guy looking at the girl walking past while his girlfriend's like "WTF" with Captain, Mach Rider, and Samus in those positions respectively. If Mach Rider is a man (which is more likely if the Melee trophy is anything to go by), then meh, as all those benefits I've stated go out the window and at best, Captain Falcon and Mach Rider have a rivalry.