I'm a fan of Rimowa and the original cabin bags are pretty safe size wise for international airlines. I also don't like how some of the US luggage brands make carry ons that are too large. I struggled to use my cheaper luggage after the rimowa because of how nice it rolls. If you just don't want it because you think it's gotten too common maybe consider the classic which is less common than the original (and you can customize a bit), the twist, or one of the limited edition/collab versions which are much less common. You could also just get an original and cover it with stickers, get an artist to paint it, or make it your own somehow.

I think the tumi looks nice but i chose the rimowa over it because of the weight which to me was noticeable and I kind of preferred the 2 compression panels over the tumi zipper.