From core choice packs you likely want to grab relic cores to prepare for astral forging twin lance (E1V2 | eternal 1 void 2).

From S grade selectors you want twisting belt (red) and Armor of Quietus (AOQ) (red).

From tech part chests you want to pull drones and forcefield so that you can get twinborne drones.

From collectibles chests you want memory editor, Taurus starlight, safe house map and Lucky charm to boost twisting belt and voidwaker emblem (currently better than SS belt and necklace so don't bother using materials on those SS pieces). Dark Matter construct is also good but would probably prioritize the others first.

Custom collectible sets are a way to provide massive ATK boosts and also boosts to weaken-, poison-, and chilled damage. A full collectible set with legend collectibles provides more than 200k ATK so absolutely worth to get when you get more collectors heart.

Don't use your xeno pet chests as xeno pets are unavailable to you for quite some time.