Actually thinking about it this way, I have seen the light. CDT makes the faulty assumption that your initial state in uncorrelated with the universe that you find yourself in (who knows, you might wake up in the middle of Newcomb's problem and find that whether or not you get $1000000 depends on whether or not your code is such that you would one-box in Newcomb's problem). UDT goes some ways to correct this issue, but it doesn't go far enough.

I would like to propose a new, more optimal decision theory. Call it ADT for Anthropic Decision Theory. Actually, it depends on a prior, so assume that you've picked out one of those. Given your prior, ADT is the decision theory D that maximizes the expected (given your prior) lifetime utility of all agents using D as their decision theory. Note how agents using ADT do provably better than agents using any other decision theory.

Note that I have absolutely no idea what ADT does in, well, any situation, but that shouldn't stop you from adopting it. It is optimal after all.