Title.
Between using the ROKS-3 in Stalingrad, and the ROKS-2 in Berlin (I don’t have the ROKS-3 squad unlocked on Berlin), I can’t decide which is better. On Berlin I like having the extra fuel capacity for burning more stuff, but on Stalingrad, having more range can be a bit helpful since I’ve observed that sometimes hitting soldiers with the fire can be hit or miss.
So I thought I would ask here: do you prefer fuel capacity over range, or range over fuel capacity?
The second one
Range 
for capacity, you have the new perk
Range, always range.
The further away I can incinerate troops the better IMO.
I like to be able to dump fuel into every window before I get deep in CqC in a building.
range, the capacity is easily solve by an engineer in the squad
Range. Without the range you have to burst some flamme just to use it as cover if you are spotted.
With range you do the same except you can already hurt the ennemy.
Range. When I run out of fuel, I killed more than enough.
The one that has better range and higher damage.
Roks-2 is garbage, just like any other tier 1 flamethrower.
Range (and higher DPS).
Unless in destruction mode, then fuel capacity comes handy to keep a wall of flames burning around the objective, preventing enemies from reaching it.
Range. There’s no question about it.
Flamenwefer 41
Both.
The second version flamethrower with range to assault quickly.
The first version with more fuel to defend, block doorways.
Good thing: there’s 2 flameboy slot in the flamethrower squad.
If those were the only two factors there might be more room for debate, but the one with higher range also has significantly higher dps.
You want range to reach them before they shoot, it also does more damage and you can get a perk for another 50 fuel in the flamethrower 2