... On top of that, an altcoin values can rise or fall pretty quickly.
Isn't it what makes it more lucrative? You can make double your coins in few days
i personally prefer trading altcoin/bitcoin pair always. because i have also tried trading bitcoin/fiat and didn't find it that much profitable for myself, although i still do it sometimes when the price is volatile but trading altcoins has more benefits in it.
I also think that bitcoin/dollar is profitable only in long term and that too when you invest heavily