the smaller the kite the faster it will be.
If it is a big kite, you want it fast, but if you have a smaller kite, you don't want it fast, since it is already very fast.
So the smaller kite doesn't need a high AR to be faster.
A Toro, Aero, Hydro.. will do a good job, unless you want it to be really fast!
I prefer a kite not too fast, since if I want to do tricks with an X2 8.0 and I pull a bit too much on one side, i get warp sped until my rips hit the water. Don't like that too much...