I like Infiltrators best after playing all classes and still play all classes. I like hacking things, invisible flash, bouncing betties, and the ability to play short and very long range from targets not to mention being somewhat invisible myself in gameplay. This allows me to move to the back of an ambush and hit them from behind while the rest of my platoon continues to engage from the front. It wouldn't be as possible without a flash which is nearly invisible. Medics and Engineers are very cool also to the point that my fav sometimes slightly changes.