Enemy distinction. LW1 had relatively few alien types in it. As such, they each had a distinct niche and role and where there was overlap it was usually due to upgrades and tiering. LW2, both as a result of the base game having more as well as the relative ease of extending the base units, has many more types (though not near to the extent that ABA has gone). I feel like there's some murkiness in the distinction between all of them now. A lot of threat types are projected by multiple enemies, leaving some of them feeling a bit samey.
- Troopers: I actually feel that their blandness works, particularly early on, their role is to be unremarkable. That being said, they end up feeling kinda like filler later in the game where everything else has perks and active skills and they are just there.
- Officers: These guys are mostly good, their single active ability is distinct. Though after looking at the ADVENT General, I wouldn't mind seeing some of GTS (or unique ADVENT) officer perks on them and watching them shout orders at all the troopers. Make them feel more like officers and less like "jerks with tacsense".
- Grenadiers: Giving these guys the utility grenade types helps here as HE nades are everywhere on tier 2 & 3 ADVENT. Though, I often see the Engineers shooting instead of flashbanging XCOM. Apparently ADVENT hasn't caught on to the flashbang pro-strat yet.
- Gunners: Probably the least defined of the ADVENT soldiers. Since the main feature of gunners is suppression and MECs and Mutons can also suppress, the gunner kinda lacks distinction until they start getting more gunner perks at higher tiers. Especially since it feels like they don't actually even suppress that often compared to other enemy types and just take a lot of shots at units in high cover, like troopers with bigger guns.
- Rocketeers: Super-clear role and threat. Perhaps the threat of environmental damage from the rockets is a bit too oppressive when a pod spawns with two of these puppies, but having the rockets limited to yellow moves gives options to work around them.
- Sentries: This is probably one of the most defined ADVENT units. RFA and all of the overwatch perks gives them a clear enemy role with a narrowness that can be planned around.
- Sergeants: I'm not actually sure what this guy's role is supposed to be other than "that jerk BAMF with tacsense". They sorta feel like a trooper decided he wanted to be a Muton when he grew up.
- Scouts: These shadow-step jerks would actually be a real clear role if Sidewinders didn't exist. They make sense and they fit into the lore and feeling of the ADVENT forces, but I don't get what they're supposed to do that isn't also done by a Sidewinders (which have similar FL deployments).
- Commandos: Sorta like bigger scouts, but with some AP? I stared at the stats and perks for these guys for a while trying to puzzle out what their tactical niche was supposed to be. Maybe these guys could get HEAT grenades or some other sort of perks to make them dedicated anti-armor skirmishers. Other than basically having AP rounds, all they have are defensive perks, which just makes them hard to kill, but not particularly interesting.
- Stun lancers: Less suicidal than vanilla, still jerks though. That being said, unless already close, the tweaks to their AI that make them less suicidal, also make them more like troopers with poor aim when they don't lightning reflexes YOLO charge.
- Shieldbearer: Their active gives them enough of a niche that being otherwise just a beefy trooper is forgivable.
- Vanguard/Shocktrooper: I like these guys from a design perspective, their perks give them clear roles as to what their threat is projected as. (Though the crit-stacking shocktrooper may be the biggest jerk ever.)
- MECs: Low tier mecs are basically robot Mutons in terms of the tools available to them, while the high tier ones stack so much armor they start to bleed over with Andromedans. Personally, I think they could afford to lose suppression. ADVENT has several sources of it and the MEC is the least reliable source since they can be hit so easily.
- MEC Longbows: "Fragile artillery MECs" I like the idea of what these are trying to do, but I never actually see them do it really. Since they are so easy to kill and don't have even limited squadsight (i.e. snapshot range), they don't stay far enough away from the guns to not get blown up right away. In my experience they tend to just overwatch on reveal and prey to the machine spirit that they don't get shot.
- Sergeants and Mutons - Tough, heavier infantry w/grenades
- Gunners, MECS, and Mutons - Suppression
- Scouts, Commandos, and Sidewinders - Shadowstep flankers
- Heavy MECS and Andromedans - Superheavy armored artillery
A lot of these concerns tie back into some of the discussion about the universal effectiveness of flashbangs in turning off units and their abilities, but that conversation is elsewhere.
All of that being said, and not particularly well I'm sure, I've been having a blast playing LW2 and look forward to many more hours of getting all my soldiers killed by dumb mistakes.