Ranger Veteran scales extremely well into Versus. You get potions and bombs galore with every special kill, and crossbow bodyshots everything easily. Handgun I think is too slow for this mode. Big ammo might be a pick if you have another dude that's ammo hungry, since this mode already throws potions and heals at you. I prefer Surprise Guest over heal / bomb dupe talents because being able to run around invisible is very strong.
Movement speed is also surprisingly good here, enemies just don't do a lot of damage.
Build: https://www.ranalds.gift/heroes/4/123312/37-1-2-1/50-1-2-1/1-2-1/1-2-1/2-3-1 (properties / traits don't matter)
As for my thoughts on the gamemode, pretty fun, pretty hard to win as skaven if you aren't playing a 4 stack. "Funny hooks" = hooking someone out of bounds. I hope fatshark continues to work on this because having an FPS background and vermintide experience I'd love to play it more often and git gud.