I use to work in MK and know them all well...I would definitely go for LTT! The plaza is okay, much better choice for lunch though. If you want lighter/less costing dinner, then yes the plaza is a good choice. But, if you want a good dinner that will fill you, the its LTT. As for Tony's, you will get a lot of people that love it there, however I don't think its that great. It is italian, but I don't think it is as good as the other italian restaurants on property (Epcot, DHS). We just ate at LTT in the fall and it was still as good as I remember.
The lunch at LTT is good, just not cheap. Like I said above, if you just want good sandwiches/salads for lunch, the Plaza is a better choice. Tony's also has good soups/pizza/hot subs/salads for lunch.