>>715571626 (OP)For souls?
Strength. Slightly.
Strength is more versatile and lends itself to more playstyles, while Dex is somewhat more limited.
With Strength, you can two-hand to improve your stats, something Dex doesn't really benefit from.
With Strength, you can equip bigger shields, something Dex cannot be used for, that it offers nothing in exchange for.
With Dex, you are mostly limited to daggers, one handed swords, curved greatswords, spears, some halberds, bows.
Meanwhile for Strength, literally every weapon category except bows and I think Whips, has something you can use that's pretty good, including some that really, nobody but you can use, like Greathammers, which are often some of the best weapon types, period.
Two handing also gives Strength better synergy with casting builds, since you can two hand your weapon until it's time to actually cast, and use better weapons while doing so than Dex would usually let you get away with. Strength can do almost everything Dex can do, but Dex cannot do some things Strength can do, essentially, and two handing makes it a better stat to have partial investment in, over Dex which is very often a stat non-dex primary characters want to keep as low as possible to use one specific thing.