I'm reconfiguring a whole bunch of things on my machine. In the process, I couldn't bear to install Aptana 1.5 again. I've been using it for a year or so since ZDE went over to Eclipse and became even more horrible to use.
Aptana is also Eclipse based which doesn't fill me with Joy but 1.5 did have excellent PHP support. My love affair with it was not long lived though as the 2.0 release last year completely decimated everything that had made me move from ZDE by dropping Aptana's PHP plugin for PDT. I've also recently had a complete nightmare helping colleagues getting Aptana 1.5 to work on Ubuntu.
I'd really love something lighter. TextMate is sleek, simple and beautiful but just doesn't cut it for me when it comes to code completion - I've come to rely on that for bigger projects and it's just too hard to go back! Netbeans is actually surprisingly good now although it is Java and getting close to being Eclipse-like.
In the end, I've been pretty impressed with Komodo Edit.
Still Java I guess but [Not Java so] it feels a lot lighter than Eclipse, supports pretty much all the main features I use constantly in Aptana and generally seems good.
I'll stick it out for a bit and see how it holds up once I start doing serious work.