Hilariously these two squad packs as-is work well together. Krennic and Vader do a good job of kinda battlecruisering the team's way wherever the hell I want to them to go. The death troopers are extremely durable and can advance very well (to capitalize on bonus dashes or advances a la Vader). Krennic himself goes without saying as hilariously good, as he does a wonderful job shutting down aggro-ey plays by negating opponents' wound momentum (LMAO). Vader is also just phenomenally strong on the field. Runs in, slices 'em down, easy peasy. The shoretroopers conveniently fit right in with Krennic but don't need any specific range to synergize, and are therefore sent to go with Vader's squad.
My initial gut reaction was to use dark troopers as well, and just have a gigantic battlecruiser of a team. The only reason I went with a stormtrooper thing is the squad point distribution (it's atrocious). Vader only gives 7SP so something's gotta be 3PC, and unfortunately the literal only Galactic Empire secondary that does that is the sarge. Couple onto that the fact that dark troopers aren't tagged 'stormtrooper' and we're kinda just cooked. Guess there is some luck that shoretroopers have the right tag, though, because raw stormtroopers aren't as fitting here.