You can not ask for the ultimate kite - without saying what you are looking for ?
Unhooked or hooked ?
Strapless or strapped ?
Kite parked or aggresive ?
Gliding on a powered small board, or on a bigger "surfing" board with smaller kite ?
Onshore or sideshore or slight offshore conditions ?
VERY difficult to answer, even if you know above
As each will have their own taste
Hey - now we have found the ultimate surfing kite: The kite you have now
Okay - to get back to some of the "topics" and compromises :
A low AR kite will turn really fast and tight - good and required for waveriding, especially in bigger sizes.
A high AR kite will turn slower, but search for the edge of the window better (accelerate with slack lines when going with the wind), so dont "slow down" or get "sluggish".
Above differences can also be obtained to some degree with profile and other design parameter changes
That is one of the aspects I see, and look for myself.
Kindly, Peter Frank