I was using Pentadactyl about a year ago but I don't remember why it was better than Vimperator.
A few days ago I switched back to Firefox and Pentadactyl wasn't available for FF36. So I'm back to Vimperator + Tree Style Tab + Toolbar Autohide. Its a terrific setup, can't recommend it enough.
Pentadactyl's ("5digits"?) build system is broken, and they haven't released a stable version recently. I publish my own personal builds from the unmodified source at this location[0], if you're interested.
Any highlights on how the two differ today? I seem to recall briefly using pentadactyl as vimperator broke something, perhaps "it's all text!". I don't understand how people can stand vimium - but that's probably because I've grown used to vimperator more than anything else.
I've never used Vimperator. I do know that Pentadactyl is far, far better than any solution I've ever used on Chrome because of how well integrated Firefox extensions can be and how limited Chrome extensions are (can't run on Chrome Store pages, can't run on builtin pages, can't run on file URLs, can't launch external programs, etc).
It's just their build system that's broken -- the code itself is fine; and works with the latest Fx. I'm using Firefox 36.0.1 right now with the builds I publish. The source is pulled and the extensions built every single night at midnight CST. Builds are located here[0].
A few days ago I switched back to Firefox and Pentadactyl wasn't available for FF36. So I'm back to Vimperator + Tree Style Tab + Toolbar Autohide. Its a terrific setup, can't recommend it enough.