I second the Pirates Dinner Adventure. We went to see it a few months ago and had a blast. The group of us (3 adults) all loved it, as did kids all over the place. It had good food, interesting entertainment beforehand and during the show itself. My only complaint was that if you are seated near the back, it can be quite dark during parts of the show, which was occasionally frustrating when I was trying to eat.
We also went to see Dixie Stampede around the same time. I didn't care for the pre-show (far too corny for my tastes), and the food (while good enough) had very small portions. By February, they will probably be back to their "regular" show. Last year, they continued their Christmas shows well past the end of December, but I don't know how long.
My last experience with Medieval Times was about two years ago. The food was downright awful and the main show "okay but not great". They have a new show since then, though.
I have not been to see Arabian Nights, but I have been told by many other locals who have been that it is "the least value among the Orlando dinner shows".
Those are the big shows in Orando, I think. Ironically, I'm going to the Polynesian Luau at SeaWorld tonight. I'll try to remember to report back about it afterward.