For portability, the best kind of projectors would have to be the small form factor pico-LED projectors. The downsides are that they aren't as bright and usually have sub-HD resolutions. However the upsides are that they are very portable, have up to 20,000 hrs of life, and are great for most general purposes as well as gaming and movies. As for which model specifically, I am a big fan of the Optoma ML550. It has 500-Lumens, 3D capable, and is ultra-portable.