I have no real input on best donator item to powerlevel people, though going by your 4 groups you probably dont need any.
The only item i would suggest (though it doesnt power level at all) is the treasure map to summon Lillu's Augmentation Distillers on your main tank.
You can't move augs from one piece of gear to another, so every time you break into a new tier and loot an upgrade to a piece of a equipment you'll have to either use the new piece without an aug (which might or probably will be a downgrade on the combined stats of the previous piece, especially when you start getting to multiple slots), or hold off on using it until you go farm new augs to put in it / wait for new augs to drop in the new tier. But where's the fun of looting new gear if you cant use it straight away?

If you can summon these distillers, you can immediately swap the augs over, pop the new piece on, and keep going. It's really important your main tank has the very best gear available to them, so you'll want the best piece you have with the best augs you can, ideally without having to refarm them every time you loot a new piece (which might not even be possible if you have Event augs).
Personally, i only have the map on my main tank and everyone else just goes augless, so main tank is the only one that really needs it.