I write my Nim code in Vim. I've never had any problems with auto-suggests.

My Vim config for Nim can be found here: https://github.com/jboy/dotfiles/tree/master/vim (based upon https://github.com/zah/nim.vim , with a few improvements to my taste).

In particular, Vim syntax highlighting for Nim: https://github.com/jboy/dotfiles/blob/master/vim/syntax/nim.... and some convenient Vim mappings to jump around in Nim: https://github.com/jboy/dotfiles/tree/master/vim/ftplugin/ni...

I also use (and recommend) the CamelCaseMode Vim plugin with Python & Nim.