Depends what you need to do. If you're interested in building straight-forward dynamic websites, then perhaps PHP would be the easiest. App building, e.g. Android-flavoured, may point you towards Java. Either way, it's deciding on the best tool for the job. I'm biased as I love php for its simplicity and it's almost code and go. My (limited) experience with Java, on the other hand left me very frsutrated. But that's just me. Java may help you to develop better OOP skills, as PHP is too flexible and allows all sorts of horrible procedural mongrelism.
You have to remember that Java and PHP are completely different languages, so, it's really difficult to suggest which one will be better, because it hugely depends on the situations and the development projects. Let's assume that you were developing for the web, using a Java Applet for a web project might seem like a good choice, until you take a look at all of the security risks associated with this (hence why there are very little java applets online today!)
I couldn't agree with Diafol any more, +1. I love PHP, it's fun because it's challenging. It's useful because it works.
I too have very limited experience with Java and it's just a different world in comparison to PHP.
Ultimately it depends on what you'd like to do in the future, PHP and Java, imo, exist for very different reasons.
If you're considering your career then there seems to be a lot more work for certified Java experts who have built themselves a portfolio of their personal projects. Getting employed as a PHP programmer is difficult as it's quite a saturated market in comparison to its demand.