Neovim's async already has tremendous plugin support and is most obviously felt in new build plugins like neomake that do async linting--no more locking up the interface on saving, and this already works well.

Neovim's embedded terminal also works great and is something vim doesn't have.

Neovim is simple to try out because it's a drop-in replacement--all your old plugins will likely work out of the box, along with your .vimrc.