There are many great places to have your Thanksgiving dinner at WDW. I recommend the LTT in the MK. The setting is perfect -- colonial days. Its a family style meal -- so it feels like a true T-day dinner.
Remember most WDW restaurants have a theme. So may restaurants will have your turkey dinner but it goes with that restaurants theme. Example, Artist Point at WL has a Northwest Theme and the entrees offered will go with that part of the USA.