Unless you have a combat simulator that actually works for group vs group with programmable tactics and all then I don't think you can actually resolve this question by playing through a few human simulations. There's to much randomness in the dice rolls themselves to reveal anything interesting outside many many playthroughs and since the hit and damage rolls can be either high or low, etc then there's a lot room for slightly changing tactics midgame to adjust to the current situation, which can greatly skew such simulations if you end up doing any particular tactic at a time I'm not advocating for it.
I think using a mix of experience at the table, statistical modelling, and plays-through, gives a more plausible picture than experience at the table and imagination alone. Crucially, plays-through allow characters and tactics to be experimented with that players might not often choose. Your point about randomness in the dice rolls is a fair one, and that can be somewhat addressed with the statistical modelling.
With that in mind I trialled four 8th level ranged characters against a Hard encounter from KFC - 1 Ettin, 2 Ghasts and 3 Ogre Zombies. The characters were a Wood Elf SS H Ranger, a Wood Elf CEx BM Fighter, a Half-Elf Agonizing AF/T Warlock, and a Tiefling Draconic Sorcerer. I didn't stack SS with CEx for all out cheese, instead I used my
Heavy weapons only version of Sharpshooter. Stats were points buy. No magical items. The play-through drove a few observations and intuitions.
- Ranged characters can have more ways than one might expect to avoid being pinned down. Warlocks can choose Repelling, Lethargy, Misty Escape, Misty Step, even Hellish Rebuke in a way does the job. Battlemaster Fighters get Menacing Attack of course, and with their Action Surge they can get out from under, or deliver a pile-driver round. Sorcerers can Fly by Tier 2, or Misty Step, Dimension Door, Greater Invis., Blink and/or Mirror Image (neither needs concentration).
- Target-selection and focus-fire are easily as strong as observed / predicted. Less obvious, but immediately clear in a play-through, is the ability to land key c-c effects on targets to juggle position.
- Taking OAs really is the right thing to do as a ranged character. These occasional bashes end up well distributed among that party.
- I think three ranged and one full caster is often going to prove stronger than four ranged. That's something I don't think we've discussed enough: the option to mix ranged with full casters, rather than with melee. Due to the need ranged has to deliver damage as a way of controlling the fight, ranged might not be able to afford two full casters... maybe melee could find an advantage there?
- Hunters Mark and Hex were easier to keep active than anticipated.
The map was 100' by 100' forest, with no room allowed off the edge (i.e. no kiting off the edge allowed). Starting distance was mixed, but around 75'. Here is the damage record.
ABW1 33h
CEF1 30c
SSR1 50m
DSr1 Greater Invis
ABW2 25h
CEF2 60cac
SSR2 49m
DSr2 16
ABW3 48h
CEF3 36cc
SSR3 36m
DSr3 17
ABW4 34h
CEF4 7 ended
ABW 0 wnds
CEF 7 wnds
SSR 12 wnds
DSr 0 wnds
What next? It feels like a deadly encounter might result in enough pressure for a dog-piling effect to come into play. So that should be tried. I also think a two melee, two full caster party would be worth trying. Certainly a dungeon map should be tried as that has been predicted to have a strong impact (one intuition is that a full caster to put down some c-c could play a significant part.) On the other hand, my experience is that for practical reasons rather than honest ones, kiting is often more curtailed than the imagined environment could reasonably allow.