PHP or dot net which one is best to learn in web desigining

Depend on your objective. If you're going to design enterprise class application for a company, I believe that .net is more suitable. Yeah it is only run in microsoft server. I you want to design a dynamic web only (well whether complex or even simple one) I think php is suitable. Get a dirty hand on its OOP technique as its development recently are moving toward a mature OOP language... I know both are different language, and didn't share the same API (function) so it is hard if you want to master both of them in the same time. So master one and then study the second in general (overview only not in depth).