I've been using vim-wiki for years. I'm a satisfied user. It supports alternative syntaxes, and I use markdown. I like that I can link to a folder on my local machine, or a file, or a web page and it loads in the correct application. With thunderlink I can also link to specific emails and have them open in Thunderbird.

I also use github.com/Konfekt/FastFold to make the folding fast enough to be useful, and github.com/plasticboy/vim-markdown to make vim understand the right way to fold.