My tiers were mostly cosmetic but in order. Maybe Swerve should have been S and everything else moved down from there.
I hope I made it obvious but I think the Swerve Star is the best, instant acceleration and (IIRC) the highest top speed outside of the Formula Star make it really dumb. Learn the courses and learn when and how much to turn and I bet it could hardly be challenged. Its gliding is even decent.
I didn't put Jet in S because I didn't know if I just liked it or if it was that good. The instant boost it gets whenever it goes airborne and the additional boost when it lands are pretty nuts though. The Scooter I just wasn't sure on. And yeah, I probably overrated the Warp Star, but it's a solid all-arounder. The Turbo Star is also really good once you know how to handle it but it can't glide. Slick is nice but it does have occasional flaws. Good glider though.
MK being good makes sense, he has good top speed, acceleration, and gliding, right? Just no boost.
I didn't play with machine health on and I don't know how that would impact the tiers (Shadow Star might be better) but the Bulk Star would still be crap. Lots of health means diddly when you can't accelerate when taking damage (the Hydra also has this problem).
I liked the Jet Star, Slick Star, Turbo Star, and Warp Star.
When Sakurai takes back over Hal.
AKA never.
IIRC KAR was the last Kirby game he worked on/directed, which is sad since he invented the series. I think it was the first game that had the colorful menus and checklist achievement system he's become known for, though.
I'll admit, I didn't care much for Top Ride but the other two modes were quite engaging.