Seriously. Is there a good list of tools that provide it? In Python, the only one I've managed to love is PyDev. Supposedly Atom does it with the "script" package?
I've been working with PyCharm [1] a lot lately and I've come to like it a lot. Probably the best context awareness I've seen for any dynamic language - it (almost) feels like working in something more tool-friendly like Java in that regard.
Really?
I used Aptana, which includes the Pydev plugin. I notice everyone seems to give PyCharm lots of love, and have been tempted to try it. Autocomplete is one of the features I rely on heavily.
I used Eclispe/Aptana/PyDev at a previous job and it was pretty nice, but PyCharm is superior in my opinion. In addition to great completion and code navigation, it also gets Vim emulation mostly right. PyCharm is also a mostly out-of-the-box experience, whereas it took a while for me to get Eclipse set up just right.
Jedi is really good. There are plugins for Vim (of course) too.
Personally I believe that things like Jedi - external static code analysers in form of a library - are what we should be doing. It's not good for IDE writers - it lessens vendor lock-in - but for the users it's a win. Having the same, very good, completions in both Vim and Emacs made my life much simpler.
I use Intellij with the PyDev plugin as my IDE and Atom (with the script package) as my text editor. In general unless it's a really quick edit PyDev is MUCH better in the general IDE functions, like autocomplete, jump to definitions, visual breakpoint debugging, etc.. I love atom but Intellij is much better for serious dev/debugging sessions.
I really REALLY dislike eclipse. In fact it would nearly always be my last choice for and ide. In my experience it's slow, buggy, bloated, and in general the features that I need work FAR better in Intellij, Visual Studio, Atom, Sublime Text 2, Emacs, or VIM. I've used pretty much all of them and I would rather go back to them than use an eclipse based project.
[1]: https://www.jetbrains.com/pycharm/