Whats the best use for the new orb currencies?

Ancient Orbs can also turn tower shields into Tukohama's Fortresses. Make that roll and you get a pretty fair amount of bank, and it's still a lot more likely than Headhunter's. Also doesn't cost you Zana money to try every time you put an Ancient together. The way I hear it though, a lot of folks hit flasks with Ancient Orbs and hope for a Taste of Hate or Sin's Rebirth.

Binding: great for generating leveling items in your twenties and up, when 4ls can be a pain to craft. It was especially awesome early in the league when currency was less available, but it's still nice to have the option.

Engineer's: save for Diviner's strongboxes,remember to use them if you find one. I didn't, last night >_>... Still pulled a fifty-chaos card from it, though! But yeah. Not really worth the investment on anything but Diviner's or high-level Cartographer's. Would not recommend slamming twenty of them on a unique strongbox. Save for Diviner's, proceed with day.

Horizons: good for filling out Atlas completion if you don't spend a ton of money (and also time and frustration) getting people to sell you lowbie maps to fill out an Atlas with.

Harbinger's: upgrade red maps into Beachhead, T15 maps into Guardian maps, or otherwise get much greater value of out high-level map drops. Or sell to other players for money so they can do the same.

Annulment: Tricky. If you've got an item with a couple of really nice mods but then also a bunch of filler, you can try and slice off one of the filler mods to give you room to slap a mastercraft on it. If you're a high-level crafter who actually uses exalts, you can try and make room for a good Exalt and hope you don't slice off one of the money shot mods. Total gamble, but could be good to turn an almost-sweet drop into a much sweeter drop with a bit of luck. Or you can brick your item. That's how crafting works!