I love Vimperator - unfortunately, it's incompatible with e10s (multiprocess Firefox) and it is also completely dependent on the deprecated XUL. Replacing that would essentially be a ground-up rewrite[0].
It looks like Vimperator is likely not going to be updated to work with newer versions of Firefox, which is a real shame, because it works far better than any alternative I've found for either Firefox or Chrome. I even made my own with the new Firefox API to see if I could replicate the experience, but it's tough[1]. The WebExtension interface doesn't give the same level of control that XUL did, and without which it's hard to give the same feel of Vimperator.
[0] https://github.com/vimperator/vimperator-labs/issues/211