If you want a browser engine it's either one of the KHTML descendants or Firefox. The problem is, both are ridiculously complex, only one family has the backing of three multi-billion dollar giants, and the other infamously suffers from "progressive disease" aka complete unwillingness to move fast and instead preferring to engineer the "perfect" solution.

That even Microsoft couldn't manage to keep up with progress only shows how utterly impossible it would be to kickstart a browser engine.

(The fact that Mozilla as an organization is embedded in constant infighting and utter incompetence doesn't help either)