So i've been asked to post what i think is a reasonable setup for a playthrough with A Better ADVENT, so you stand a chance against the difficulty that is considerably higher than vanilla.

So here we go:

0 - A Better ADVENT 2
Duh.

1 - Class Mod
You are going to need some sort of class mod, because the vanilla classes just don't cut it anymore. I suggest going with the Long War Perk Pack and then either using it out of the box or modifying it with another mod. My personal favorites are the Paragon Classes and the Shadow Ops LW classes, but there are a ton of creative and well done class mods on the Workshop.
Long War Perk Pack: https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=719109968
Shadow Ops classes: https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=790582498
Paragon classes: https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=732939977

2 - Squad Size upgrade
Thanks to the Better Pods integration in ABA, you will not be happy if you try to make your way through with 4 rookies. Upgrade your squadsize from the vanilla 4-6 to 6-8. That way, you will have an easier early game, facing pods of 4 enemies with 6 soldiers. But in the endgame you'll run into pods of 7 enemies with 8 soldiers, making the whole thing a lot more ... interesting.
For the squad upgrade, use the LW Toolbox if you can. It has the superior UI and is worth the hassle. If you can't use Toolbox for compatibility reasons, Larger Starting Squad is a decent alternative that i have used before.
LW Toolbox: https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=674832831
Larger Starting Squad: https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=619922328

3 - Timer Extension
More enemies means you will take a longer time to get your mission done. ABA already has a solution built in for terror missions (you get additional civvies in those missions), but you still need something for Protect Device missions and for Timer missions.
For Protect Device missions, there's (as far as i am aware) only one solution:
Configurable Protect Device: https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=634951246
For timers, there ar e a couple of solutions, my personal favorite is TimerTweaks because it's simple and just gives a flat +4 turns to everything. True Concealment is a decent alternative, i suggest the version with the default timers.
TimerTweaks: https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=616857663
True Concealment: https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=619816174

4 - Other
Due to all the extra enemy variants running around, you may be wondering from time to time what all those guys are. Does the Shieldbearer have a Shotgun? Or is it a regular one. What about this Archon? Is it a variant or vanilla? Wait, did that Sectopod just move? ♥♥♥♥ it's a Prime! Abort! Abort!
To give your poor eyes a break, you should use the mod "Additional Icons" to add nametags to the units. That'll give you a much better overview of the battlefield and makes it much easier to grasp what you are dealing with.
Additional Icons: https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=646244015
I strongly suggest going into the ini and disabling the Loot indicator, though. It's a bit cheaty for my tastes. But you do you.



On top of those, you can add your regular set of mods from Gotcha and Soldier Fatigue over Grimy Loot and Scanning Sites Plus to the Tiny Tina voicepack and Danger Zone. You know, the essentials.