What is the best choice for a Touch screen LCD powered by arduino Mega 2560?

I am working on a project where I need to create a Custom GUI with a Touchscreen Display that will control a couple motors and read inputs from 3 sensors and send data the microcontroller to determine what is displayed on the screen. I will be using two easy drivers for the motors.

I have been searching the internet and am having trouble choosing the Touchscreen I want to use, I would like it to be bigger than 3.5" and smaller than 8". It must be compatible with the 2560. I am open to a screen smaller than 3.5" but no smaller than 3".

I would like any suggestions and the reasoning why that would be a good choice. The reason I am posting here is because the design challenge is finding a microcontroller that doesn't hog all of pin resources on the 2560 because I have to have at least 13 other Digital I/O pins for my motors and other sensors.

Well, you could be picking up the “design challenge” with the wrong hand. Analogue pins A0,A15 can be used as digital and I have never heard of any LCD that uses any of them.