Which name is better? Other suggestions??

You have a great list! My favorite is Kyson, it's very unique and the nickname of Kai would be awesome. I really like the name Kason or Casen, however you want to spell it. There's Bryson (Brycen) or Trason, pronounced Trey-sen. Oliver and the nickname Ollie are great, something kinda similar would be Orrick and call him Orrie. Hope I helped, good luck!