what to look for in a quality flashlight?

[trbofrek]

Hi I own a surefire 6p and several other chinese flashlights and recieved a very cheap xpe 3 pack flashlights for only $20 dollars. Just from the appearance and feel compared to my other flashlights it seems closely to the build quality (still not on par to my 6p or tk12). I just want to get other forum members' opinion on how to determine quality vs crap (internally and externally). thanks!