This is VERY simple.
If all your going to be going is watch movies and videos then the sp4805 is the clear choice.
If you want to do both watch movies and hook up to your PC then the Optoma is the winner out of the rest of them. Im not going to get into detail of why, just know this is coming from a projector expert. You guys/gals really seem to know nothing about the most important aspecs of these units such as naive resolution, color wheel information, color wheel segment info. lumens, C.R., dbl level of each, ect ect ect...