I have found that Netbeans has better code completion than Aptana. When I was working with codeigniter, Netbeans would code complete for my static methods in models where Aptana wouldn't.
Since my posting of this, JetBrains has released PHPStorm and has your rapid fire intellisense, as well as even better type hinting. It is absolutely superior to all others IMHO. I've been using EAP 2.0 for several months now for free.