If you are writing applications that support a web site then you could probably choose any of the languages mentioned. Each offers a number of advantages and disadvantages that need to be considered. Many have been covered in this thread but here are a couple of mine!
If you are developing code for yourself (school / college project, hobby etc.) then you should use whichever language you like / know best. If you are developing code for someone else then you should choose the tools that are known by the majority of the coders or technical staff so that the code can be maintained and supported after you are gone.
Code in an environment that is best suited to your target environment. Most hosting companies support ASP by way of ChilliSoft but a perl script might be easier to deploy.
Whichever language you choose to develop stuff in - enjoy yourself while you do it!