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 entirely true. Look at PHPs track record for PHPs security itself, not programs built with PHP. There have been numerous web worms and other types of malicious programs which are only viable because of functions in PHP itself that are vulnerable. They generally patch PHP pretty fast, but upgrading your own installation can be a headache when you have to do it every other week.