In my experience, types which prove certain properties are usually a lot simpler than the tests verifying the same (at least tests which actually have a good chance of catching transgressions, instead of just checking a single hard-coded input). So more expressive type systems bring me a higher level of satisfaction, because they lead to simpler code than the code I'd need to write if I needed to test the same things. They also provide valuable documentation. On the other end of the spectrum, when I look at untyped Python code, I feel completely lost and find myself scouring the documentation for information that should be obvious from function definitions, but is instead specified in prose 3 links away from documentation of the function I was interested in.