I think uMatrix is the better extension. I use it in tandem with uBO.
But yeah, Raymond didn't have the resources to develop both at once and chose uBO which offered a more digestible, install-and-forget experience palatable to a wider audience.
Raymond basically said uMatrix was feature complete. But there could be bugs.
https://github.com/gorhill/uMatrix
I don't know the implications of that, it's the only tool I've ever found that lets me feel in control of what programs my browser is executing.