I think The Wave is a pretty good restaurant. Breakfast is their most outstanding choice, really, especially the buffet. It's a nice option for lunch, but not all that exciting for a great dinner. In the end, it's a second tier resort restaurant and I would rank them below several of the other deluxe resort 2nd tier restaurants, the best being the Grand Floridian Cafe and the Kona Cafe at the Grand Floridian and the Polynesian.
As for Be Our Guest, their dinner is absolutely wonderful and certainly top notch for a fine dining experience. I ate there last December and it was even better than the previous time I ate there for dinner, 4 years prior. As for breakfast and lunch, obviously, these are essentially quick-dining levels of quality food given to you, it's just that it is served to you, that being said, it is, to me, excellent quality for quick-service level of food. I enjoy all levels of quality of food for what they are. So, you just have to always know what your getting yourself into when you eat somewhere, in terms of the restaurant's approach to food and decide if you're ok with that. For me, I thought their breakfast and lunch choices, of which I have had several each over the years, to be very satisfying and fun, from breakfast sandwiches to lunch sandwiches to that quiche thing which is quite yummy.
You can certainly get better quality breakfast and lunch with more frills and excitement and bigger portions at resort eateries. However, the ambiance at Be Our Guest is special and it is a quick and efficient meal that is very solid.
So, you weigh all the options and pros and cons and decide what is best for you. Me, I try to always include BOG in my itinerary for sure, because to me, it is a special overall experience I would miss. The Wave gets included only if it fits into my schedule. It's not a "must".