I will choose Bitcoin and Ethereum Classic for retiring. I think the reason is not much different from what you have mentioned above. Bitcoin has the highest rate than other crypto coins and it seems will survive for a long time since it's like a parent of crypto coins. While Ethereum Classic has a very promising future, Its popularity will develop more and more.
Bitcoin would be fine idea but why you want to take the ethereum classic as a future investment after retirement dude? It will be no more use in this crypto currency marketplace in some years. So after 10 years you checked for ethereum classic to invest means it will not be in use for sure.
Then I have suggestion along with bitcoin, that is ethereum. This is the currency is been widely used after bitcoin so usage wise also everyday it is getting increased in the market.