I’ve pulled Gilgamesh and Jalter and while I’ve made both 60+ who should get more focus?
Gil -> Jalter.
Both are powerful. Gil however, after all of his upgrades, stands to this day as one of the most offensively versatile and consistently chart-topping Servants in the entire game. He’s an excellent boss-killer, crit beast, and can pull double-duty for harder content as well as farming in all manner of circumstances save like Lancers. Once getting Gil to L90 and getting all his upgrades, you can see how you feel about Jalter.
Gil works better in the long run, his Noble Phantsm hits many bosses for Single target levels of damage while being AoE. Has a charge skill so he can farm pretty well, and can make his own stars to crit with his face cards consistantly.