undo-tree is great! I use it like a "mini git", it supports branches/forks, so I can usually just try something in any order and easily go back to where I want to be. I use it in combination with Evil (vim) bindings, and everything works like a dream.

Trying it out for the first time. Love this line in the docs:

"The only downside to this more advanced yet simpler undo system is that it was inspired by Vim."

I'll second the recommendation to use undo-tree. If your undo history is going to be tree-like, which it is in Emacs, then you might as well be able to visualize and manipulate that tree directly.