In face to face we're somewhat limited to what we can actually bring (so for me it's Munitorum Armoured containers, ruins, and "craters" made of scatter terrain), but in TTS we have a bigger palette to draw from so we've seen a few variants.
It seems pretty easy to slip into the extremes of "can't hide anything from first turn shooting, game potentially decided by first turn roll off" and "horrible maze where you can't see anything and psychotic vikings jump out of nowhere to massacre you". Avoiding those is first priority, after which variety probably matters more than anything else, followed by provoking interesting decisions.
I feel like:
- There should be firing *lanes* into deployment zones, say two fairly central ones, or one central lane and on the sides. You should be able to hide a lot of stuff, but the tradeoff would be when placing objectives a more shooting focused player can make sure to put at least one in the lanes and make it awkward to get to them from hiding.
- The blockers that create those lanes should be a mix of hard LOS blockers (eg container stacks) and Obscuring (eg ruins). The LOS blockers will usually be better for avoiding getting shot, but are harder to deal with movement wise. The Obscuring stuff is interesting because of the tradeoff between staying outside (and blocking LOS) and moving in (and having mutual visibility to a *lot* of stuff). A mistake I've made a couple of times is making the obscuring ruins too big - if everyone can move into them right out of deployment they may as well not be there. I've also done double L blockers and that's probably too much on the smaller board.
- Having hard LOS on one side and Obscuring on the other is probably OK? You just need to consider both directions on the board. That might mean if you set the board up so that the (more common?) short edge deployment has both LOS blocker and obscuring terrain are accessible from both deployment zones, on long edge deployment one zone will be close to a lot of LOS blockers and the other will be near a bunch of obscuring. That is probably OK since it makes the attacker vs defender decision consequential.
- There should be cover options in the spaces remaining - some things like craters that give light cover in return for a movement tradeoff, some barrier type stuff that gives light cover from one direction but doesn't hurt movement, some dense cover to slightly offset shooting. For face to face play good to be clear on what this stuff is vs any random scatter terrain that's there for looks.
This is all in the context of only being 2xKill Team boards though, there's not actually that much room

What does everyone else think?