[SebNag_]

Missing the most important one:

https://valloric.github.io/YouCompleteMe/

:)

[nerdwaller]

I’ve moved from YouCompleteMe to Deoplete. While YCM is good, the plugin support for deoplete seems a bit more extended and easier to set up (ymmv). Maybe I just messed something up every time I tried to rework my vimrc with YCM though, it’s probably likely :D

[steeef]

+1 for Deoplete. As long as you're using NeoVim or a more recent version of Vim (8.0+) with a few plugins, it just works.