Primarily I wanted to write my own extensions in an integrated language with a good, honed, text api. Vimscript is really not so nice, and Emacs has a fantastic text / editor API that's a pleasure to work with.
Other features that were important to me were
- Org Mode (I'm using it for all documentation now)
- Usability: As described below, every function in the editor can be accessed with a quick command (with pattern matching to find the correct one) vs. knowledge of arcane commands in vim. Also, most modes offer convenient access to all their features in the menu bar. So when I'm using a Clojure mode, and I can't currently remember the correct command / keystroke for changing the current Repl namespace to my current file, I click the menubar and there it is. All neatly listed. Makes it a lot easier.
- I like the Emacs way of having all in one window. I have one big fullscreen window with multiple buffers, and in there I have a terminal, a repl, multiple code windows, html documentation. So I never have to leave that mode. Keeps me productive. That is also kinda possible with tmux and Vim, but then I always had overlapping keyboard shortcuts for switching windows. All in all Emacs works better for me here.
- Lots of small things, in general Emacs feels like a much more solid editor, with more configuration options to fit it to my liking.
Lots of people dislike vimscript and although I think you can also write plugins using python, it also seems more difficult to interface with.
I know that you can have a big fullscreen window with multiple buffers and a terminal and a repl in terminal vim without tmux. I guess you are not interested but you could see multiple buffers with :vsplit or :split to get vertical and horizontal splits, respectively. There are plugins for a terminal/repl.
Org mode sounds interesting to me, one of the things that I miss from eclipse is that I could see the javadoc when I held the mouse over an object/method/function, is that what Org mode does?
I know about vsplit and split, what I meant was a better terminal than conqueterm. Now, the Emacs ansi-term is also not perfect, but way better than Conqueterm.
Org mode is a very sophisticated Todo and documentation and wiki and calendar and management and literal programming system for Emacs. I haven't found anything that compares to it. It is really really good.
The java doc thing is something entirely different, and that's usually made possible by the various language modes.
Other features that were important to me were - Org Mode (I'm using it for all documentation now)
- Usability: As described below, every function in the editor can be accessed with a quick command (with pattern matching to find the correct one) vs. knowledge of arcane commands in vim. Also, most modes offer convenient access to all their features in the menu bar. So when I'm using a Clojure mode, and I can't currently remember the correct command / keystroke for changing the current Repl namespace to my current file, I click the menubar and there it is. All neatly listed. Makes it a lot easier.
- I like the Emacs way of having all in one window. I have one big fullscreen window with multiple buffers, and in there I have a terminal, a repl, multiple code windows, html documentation. So I never have to leave that mode. Keeps me productive. That is also kinda possible with tmux and Vim, but then I always had overlapping keyboard shortcuts for switching windows. All in all Emacs works better for me here.
- Lots of small things, in general Emacs feels like a much more solid editor, with more configuration options to fit it to my liking.