I'm talking stuff like Monero, XLM, etc. With BTC so high, does it make more sense to trade them for BTC, or for USD?
It depend on the holders of the coins dude, Because we had our belief in the altcoins. Just like for example, I like Bitcoin, Ethereum, Dot, Nem, Link, Ada and Vet, these are all good to me, but not Xlm and Monero, Though I am not saying they are not good to hold in the long term neither in short term trading, of course not.
At the moment, probably all cryptocurrency users will agree that the most profitable asset for investment today is Bitcoin
ethereum. And no one will argue with this, because already this year we expect a fairly large-scale growth of these cryptocurrencies. But you also should not forget about other cryptocurrencies if a person has good capital, at least which are in the top ten of the coinmarketcap rating. In addition, each user has their own preferences for new projects that can show quite good results, such as AME and YOUC.