What Server Technology?

Hi all,

I recently decided i am ok at Actionscript 3, well good enough to move on with some other stuff.

I am looking for a role as an Actionscript Developer so its time for me to hit some applications using the Server.

One of the things i have noticed when looking for roles is that different jobs what different things. Some want PHP, others want ASP.NET, others still want Ruby. Well my question is, whats the best one to go for?

Id like to do many things with the server but i dont want to just have a CMS, i need to be able to understand what is going on from stratch on the server.

Can anyone give me advice?

EDIT:

Sorry feel free to move this to the server-side forum.