Which top 30 coinmarketcap rankings are most undervalued and why do you think this?
For me, if you want some high-risk high reward, go for new altcoins that are able to reach the top 30 like months - 1 year.
But just don't forget some network chain altcoin, like some layer 2 networks also. Or even Ethereum, because if you compare it to Bitcoin versus these altcoins all-time high, there's still a lot of room above just in case if we will visit all-time prices again.