MI-2 - LeChuck's Revenge is my favourite for many reasons, such as:

- It's old enough to still be one of the classics, but has more depth and length than MI-1. Great old time graphics, and original point and click system.

- Guybrush looks the best in it, and has a beard =D Where did that go in MI-3? =(

- It was very funny.

- LeChuck was scarier. He is so not scary in MI-3.

I haven't played MI-4 but I don't like seeing 3D graphics on a game like MI. =P