Obviously there is no "better" -- or more worth learning -- language at all. Which language you use is is just a matter of what you like AND what your server supports. You should not learn a language that wouldn't be supported by any server or is said to be dying in the near future. On the other hand it is obvious too that there will be even better languages in the future and that those will be more useful. So learn one that is fast, convenient and that you like and where learning it wouldn't be a too big effort because, as said, you're likely to change in less than 3 years.
I, personally would be considering an "open-source" (not proprietary) one, because the web is open to everyone and open-source is more likely to be supported by every-one. (Which means PHP in this case)