This is just my opinion, based off of likability and gameplay.
Yul (Cook Islands)
Sophie (South Pacific)
Kim (One World)
Tony (Cagayan) (Under one condition: if he were to return he would have to speak llama during his time in the game)
Natalie (San Juan del Sur)
This list is subject to change, and might be added on to as seasons progress or I rewatch seasons and decide I'd like to see their respective winner again.
Feel free to comment with your own list!