Never played XI, but I raided a lot of early EQ1. That game has since gone to an ilvl-like mess of simply playing for "+1gooder" gear. But early on, itemization was done by hand and was varied. So as a caster I would have to choose if I wanted the piece with balanced hp/mana to survive AE damage, or if I wanted to stack mana to extend my damage in a fight. Resists would be spread in chunks, so I'd have to remember to make sure I had at least one piece with each resist. Other gear would have "clicky" effects which you could use as duration buffs, burst buffs, group buffs, direct damage spells that were off the gcd/mana free, etc.