Neither. It's an irrelevant question. Programs are secure or not. You can write secure programs in any language (and it's difficult in all of them), and you can write insecure programs in any language (and that's surprisingly easy).That's not completely true (at least in this case.)
Contrary to Perl, PHP doesn't have a taint mode, which is a deficiency of the language.
Granted, you can still write secure programs without using the taint mode, but it can be much harder to detect the vulnerabilities of your code.