I've been building a gameplay overhaul for some time now, one mod at a time.
And now I've taken the time to put it together into a collection.
This collection represents a lot of my own work, but also mods made by other users that I use and recommend to you.

The XCom 2 modding scene is still young, so this overhaul still has a ways to go.
But it's quite sizeable as it is right now.

For now, you will need to take the following steps for my highlander mod:
(One of the Long War devs has told me Firaxis will automate this after the next patch)

highlander mod.

Copy the UPK and uncompressed.upk file from:
SteamApps\workshop\content\268500\658305112\CookedPCConsole for me

Use them to replace the ones from:
steamapps\common\XCOM 2\XComGame\CookedPCConsole

The main benefit is that the balance and compatibility of all the mods in this collection have been vetted by an experienced mod author.
I get a lot of questions about compatibility, and I don't have time to check everyone's load order.
But this overhaul represents what I personally use, and I'm definitely gonna vet my own load order.

Yes. it's strictly better from a feature standpoint.
Some users may be concerned that a standalone-all-in-one mod might be able to accomplish more.
That's not really the case though, due to how flexible XCom 2 modding tools are.

Separate mods can interact with each other, in spite of being separate mods.
For example, my class mods add new weapon upgrades to my loot mod.
So when you use these two mods together, you get new content you couldn't get with just one or the other.
You're not going to lose out on any content that would have been there if I had merged these mods together.

A lot of players want a big "Long War" style overhaul, and I'm going to say right now, this is NOT that.
I have not played much of Long War in EU, so I'm not even going to try to make an overhaul in this theme.

My stance is that XCom 2 has far more modding tools and flexibility than EU did, and we should take advantage of that and strive to build novel content when possible.

If I had to describe a "Theme" for this overhaul, it would be that I tried to add novel gameplay mechanics and give the player more interesting decisions.

This is strictly a gameplay overhaul, so there's few to no bugfix, voicepack, or graphical mods unless they are packaged with another mod.

This Overhaul is potentially very challenging, due to Attrition Mode and Real Time Mission Timers. You have been warned. If that's not quite your speed, feel free to remove them. This is a modular overhaul afterall :).

Free Camera Rotation
Camera Rotation is handled by my More Hotkeys mod.
You will get geoscape lag if you use this mod with this collection, due to the mod conflict.

Show Health Values and Numeric Health
Health displays are handled by my Additional Icons mod
Using these two mods with my additional icons mod will cause geoscape lag due to the mod conflict.

Nicknames Extended conflicts with Expanded Callsigns.
NIcknames extended has more nicknames, but I recommend Expanded callsigns in this collection since Expanded Callsigns doesn't have any typos, and has removed the XComGame folder as all mods should.

If you want to use these two mods together, see the instructions here

Long War Toolbox
Long War Toolbox, like Free Camera Rotation, overrides XComTacticalInput
Meaning it will cause geoscape lag when used with my More Hotkeys mod
This can be prevented by doing the following:

Go to: C:\Program Files (x86)\Steam\steamapps\workshop\content\268500\674832831\Config
Open XComEngine.ini
Delete the line: +ModClassOverrides=(BaseGameClass="XComTacticalInput", ModClass="XComTacticalInput_LW")

This will disable Long War Toolbox's control over camera rotation, allowing my more hotkeys mod to control camera rotation.
This change will also prevent any geoscape lag.

Grenade Throwing Tweaks
This mod edits grenade range. The problem is my Anarchist mod and Loot mod also try to edit grenade range.
And this is a mod conflict, though not the kind that causes geoscape lag.
For this reason, my Class Rebalance mod handles tile snapping.