Im a vegetarian also and we have been to several buffets. Im not real picky and I can say that Ive never had a problem with getting full, but the worst for food variety has to be chef mickeys breakfast. I love the place, but everything I asked about if they could make without meat they said no and then finally a chef told me sorry what is out here is what we have, its all premade. So, kinda sucked.
I probably liked Tusker House dinner best, at Animal Kingdom. It had some dishes that werent the typical Disney Buffett and they were willing to prepare some items without meat. I know some pasta dish they brought out for me meatless.
Also, I was worried about Ohanna, since its known for the meat, while my DH said it was the best steak he ever has had, I let them know I was a vegetarian and the chef prepared a huge plate for me that had rice, tofu, fresh vegetables, it was great and the salad and pasta and bread are very good too. And the dessert, WOW! Loved it and looking forward to it again!