there's a cool byerly handle for sale in the classifieds for like $60 or something. Any wakeboard specific handle will work fine. grip is just preference.
My two favorites are the Fly High and the Hardline DHS. Both are not too expensive. The Fly High is the most durable I've ever seen or used. The DHS allows you to change grips easily so you can swap them out when worn or damaged. Both will save some coin in the long run.
WATSON HANDLE IS THE BEST. I thought all EVA handles were similar and felt the same way. But this one stands out above the rest. Im getting one as soon as possible.