Yes, less age and no cracks would be good starters.

Also little brake surface wear, and no sign of impact. Beyond that roll the rim on the floor and look for rise and fall at the top (egginess), then lay it on a known to be flat table (glass tables are great for this) and see if it lays flat or is curled like a potato chip.

I never re-use rims or spokes on my personal builds, and charge extra labor when folks ask me to reuse stuff. While a newbie might be tempted to save dough on his first builds, you're probably better off with a cheap but new rim.