Since I've not been to Yak and Yeti, I can't comment on it, but I will give you my opinion on the Wave and Whispering Canyon. The DH and I tried the Wave last September and were really disppointed. The service was just so-so, definitely not up to Disney standards, and neither was the food. It was really hard to find something on the menu that I even remotely wanted, and once I did, it just wasn't good. My DH didn't care for his meal either.
Now for Whispering Canyon-We actually just ate there on our trip earlier this month, and we loved it!! We ended up getting the all-you-can-eat skillet and it was sooooo good! Not to mention our service was really, really good! We were so full that we couldn't hold dessert, so our waiter let us pick something and wrapped it up for us to take back with us, which was really nice! So, to sum it up, my pick would definitely be Whispering Canyon!