When I first started programming, I used KDevelop because I used KDE. Then I realized I didn’t need KDevelop because I didn’t use other functionalities than the editor, so, I switched to Kate which KDevelop uses as editor. I like the default font-type, the highlights, the commands, everything…
When I moved to GNOME (and now I am addicted to it) I saw Gedit and didn’t like it – I still don’t – so, continued to use Kate in GNOME
Sometime ago I found Geany, a lightweight GTK based IDE for several languages. I think it is simply wonderful! It loads in a second, always light and it supports every language I work with. The language support is not equal for every language, it is more complete for PHP than for Python for example but it’s OK. It has word completion, shows your methods and has other useful functions like replacing a word in every file opened in the editor. It even has the build/run functions!
If your computer is like mine, kinda allergic to Eclipse (it drags it’s ass everytime I do something new in Eclipse), try Geany. It SIMPLY works!
Geany web site: http://www.geany.org/