I work 100% alone. I used to have a group I'd at least share the pages with beforehand back when I'd just post pages on my personal website, but I'm not part of that group anymore, so no one even sees the pages until they're public now. An editor would be nice, but I'm pretty content keeping everything else my own. If I ever make enough money from my day job I might hire someone to edit, but who knows.
I do love doing collaborations, though. It'd just have to be a pretty short comic for me to be able to do it and to deliver to the end.