But in melee it potentially kills fewer enemies.
True. This however, is a complete moot point since the chance of that happening, or being relevant, isn't all that likely. I'll take a raw statistical average over a slim chance of sometimes being better any day of the week.
Another point, both in and outside of CC, how many units in the game are T5 or less? Compare that to the amount of units with invulnerable saves. Then keep in mind that we haven't even begun discussing which type of units you are more likely to face on the table.
Again, the protocol is obvious: The D (not an euphemism) trumps 10.
Edit; If you need further arguments as to why Str. D is better, here's some anecdotal evidence (yes, I know):
In my LGG, we have houseruled Strenght D into a much less powerful version than GW's. It's still, IMO, much better. I am even contemplating nerfing it slightly more.