If you've found some good ones, do share them in the comments. The long answer is that Long War 2 is a more complete, immersive, and fair game.
I’ll add my experience with both as a comment, but that’s the short answer.
The Steam Workshop and XCOM 2's mod management interface makes it beautifully easy to flick these on or off in any combination, so experiment away. Long War 2 is a reinvention of Vanilla which much more believably gives you the experience of leading a guerilla war. On the Avenger base view, Restored Avenger Navigation lets you pan the view with WASD again, rather than flicking between rooms. Mission Award Variety changes the awards that appear at the end of a mission-I particularly empathise with the "Hates Stun Lancers The Most" award. There are a few small, frivolous mods that are worth a look. This might feel like cheating, but you can toggle any of the stats off in the mod's. There is also an icon that tells you whether an alien is carrying loot or not. We’ll have more information about the content of these mods soon. These mods are currently slated to be available at launch on February 5, 2016. Additional Icons adds a collection of stats above alien health bars, displaying the damage of the enemy's primary weapon, their aim stat, movement range and health. The Long War Studios team, which is comprised of John Lumpkin, Rachel Amineri Norman and James JCLewis Karlson, is currently hard at work on multiple mods for XCOM 2. Perfect Information displays hit, crit and dodge figures to attacks made by XCOM recruits and aliens in combat, which allows you to laugh at aliens that completely whiff a 90 percent shot. XCOM 2's user interface is decent, but you can always have more data.