For around half a year I was using Eclipse instead of Aptana Studio. There were multiple reasons to do so: Aptana was a little buggy in Ubuntu, I wanted to use the ADT Android plugin for Eclipse and installing it in Aptana didn't really work out, I needed the Roku BrightScript plugin for Eclipse as well.
Turned out that Eclipse didn't really make me happy. The bugs in Ubuntu were even worse. Sometimes the whole IDE was simply not working. The Update Manager is horribly buggy. I had to find a completely different download for the IDE in order to make it work. Additionally each time I re-installed Eclipse I had to install all necessary plugins which took quite some time.
Finally I was trying some other IDE's. Some of them I used before, but there are newer versions so I tried them again. I finally switched back to Aptana yesterday due to the advantages listed below. Amongst the other IDE's I tried to use (again) were Komodo Edit (also need to install plugins until ready, very weird indentation rules), jEdit (not really ready to go after install either), Geany (looked promising, disappointed me, apparently also quite buggy in Ubuntu) & Sublime Text Editor (ok, not an IDE, the in-file configuration scared me away). I am not really into these hardcore Linux editors like emacs or vim and like a nice IDE with simple but intuitive design.
So I finally got back to Aptana. The advantages here are: it comes out of the box with all the plugins I need (Web coding,, PyDev, PHP), it slightly simpler than Eclipse, it has built-in browsing to terminal & file browser (which was simply missing in Eclipse), git integration, easy theming, etc.. Additionally they fixed the bugs which were annoying me half a year ago.
If some Android development comes up again I might switch back to Eclipse just for this. For everything else I stay with Aptana for now.