I do not know about the next monster to be honest rather i would say that i have high hopes about potentially big price of ADA (Cardano) in the future, i am also not into risking it all or want to spread fomo about a new coin so my second pick would be Eth because i know it will boom.
your choice is good, Ethereum is indeed a Monster in my opinion, the project is a big project, especially with the existence of Ethereum 2.0 will provide a new atmosphere for the world of crypto currencies, and I'm sure Ripple will not remain silent either, we know these two projects are rivals