I didn't decide even the language yet, but I think I'd prefer python. PHP could be fine if there is some framework that is nice enough.
I guess in the end I'll go for django and jquery since they are the most widely used options, afaik, but if I was going for the most widely used options I guess I should choose Java or PHP (I don't really like Java for my spare time, but php is not so bad), so I preferred to ask first.
I think the question has to consider both, framework and library, since sometimes they are coupled. I think this is the place to ask this kind of things, sorry if not, and thank you.