What is your preference?

First of all, they're both right.

It's Aerith, yeah. But if you grew up playing PS1, whether or not it's incorrectly translated is irrelevant. You're used to it, and it was officially localized as Aeris.

This one isn't even that a big deal. Imagine being called "Butz" lmao.

I left off the third poll option, "I just use whatever is said in that specific game", which I think is the choice most people would be okay with.

Fun Fact: In a more recent FF7 playthrough a few years back, I changed her name to Aerith. You can still notice in sentences where it's supposed to be Aeris when they signify the double S apostrophe indicating possession.