Which Eclipse distribution is good for web development using Python, PHP, or Perl?
PyDev is pretty decent as I'm sure you know. It can fit on top of all the Eclipse distributions (provided they meet the minimum version requirements). If you're doing webdev stuff, you'll probably find the closest fit with Aptana. 
That said, I find Aptana hideously clunky when compared to a decent text editor. I build sites using django and for that I use Eclipse (pure) and PyDev to do the python and gedit (gnome's souped up notepad) for writing the HTML for templates/CSS/JS/etc.
At the end of the day, whatever suits you best is what you'll go with.
I'd like to try out Eclipse, but I'm a bit baffled with all the different distributions of it. I mainly program in Python doing web development, but I also need to maintain PHP and Perl apps. It looks like EasyEclipse is a bit behind. Should I just grab the base Eclipse and start loading plug-ins?