[rsstack]

TabNine isn't open source but works with Vim: https://www.tabnine.com/install/vim

[pramttl]

Tabnine is my personal favorite as it works with most IDEs including IntelliJ, Vim and even VSCode and the suggestions are high-quality. I actually moved away from Copilot to Tabnine across all IDEs and haven't gone back since.