If you want to redo the old levels similarly to how you've done them now but a bit more efficiently/quickly, take the best of whatever you have now.
If you want to do the old levels as quickly as possible, SAC, AV, maybe TS, QS, HB, AcacheB, AcampB.
If you want to win WZIBs, AcampB, SAC, TW.
If you want to focus on the new levels, TW, IM, AcacheB, QS, AcampB, HB.
If you want to focus on next SASc, TW, IM, AcacheB, QS, AcampB, SAC, AV, HB. (you need what's good both for new levels & also EH to be able to Asc to get enough AP to SAsc again).
SAC is super useful on the old levels, not so much on the new levels. AV is a necessity on the old levels & I would say also a necessity to be able to complete EH in between SAsc's (ie: finished 1 SAsc already, trying to complete EH in order to Asc on way to next SAsc while also trying to minimize investments in P1/2/3; not having AV in this case is going to make that EH clear fairly arduous [hello mining/smelting/crafting], or force you to spend more AP in P1/2/3 than you need to get to P4).
TW to reduce the cooldowns, as simple as that. Get it to minimum Leg, preferably Insane. And if you're gonna spend some 10x TW (SP TWs), ensure to align them with actives and notably TW being on cooldown to maximize that benefit. (And digs & hospital upgrades also of course).
TS & QS are useful on both, but notably Hex, QS gives best value for the 737B territory. (Same goes for EH/HEH). But imho you need at least 1 of TS, QS, IM on the new levels. But Insane QS @ 384% is breathtaking - imagine eating the 737B territory on Hex, and seeing your armies grow from 1T to 3.1T (this can be the difference between needing to "do stuff" [crafting/use markets/upgrading hospitals, etc] vs just finishing the level with the caches), or the 1.1T on HEH and see armies grow from 1T to 4.1T. It's truly a beautiful thing. Actually maybe more appropriate to say the 404B territory on EH and grow from 20B to 1.1T. So on EH, go from "stuck and can't finish the level", to "got everything I need to get all hospitals and markets and can steamroll the level now".
IM is in the same vein as TS/QS - you need "something" to give you extra armies on the new levels, ie: something to give you armies beyond what army camps (including SAC+FC benefits) can provide. Mercs are expensive, money is often tight. Downside is that you really need to get IM to Insane to be truly useful. TS & QS are useful from Legendary. All 3 benefit from TW, again notably if you can get it to Insane.
AcacheB is good on both old and new levels, but becomes even more important on new, since they are so cache focused.
AcampB becomes less and less useful on long playthroughs of the old levels b/c your investment in IACP offsets it - but if you SAsc and focus on another SAsc with as little investment in P1/2/3 as possible, having a good AcampB can help to avoid having to put 100-300% into IACP so you can just get out of P1 asap, putting AP into just JS & Additional Mercs.
HB is good on both old and new but less value than the others listed above.
These are enough to get you through the game.
Right now I'm sticking with TW, IM, QS, AcacheB, AcampB, HB, AV. And if I get SAC through digs after SAsc, great, otherwise use powers to start a level off.
Edited 7/30/2022 15:39:52