There is no real answer.
Full Dex used to do the most of damage if your gear is better
Full Str used to do most sustained damage with mid equip
but Full DEX is most likely better if base spell damage is hig.
You need the Crit Damage Gems or Crit Ratio Gems and overall better equip.
Str add Flat Damage and Crit Damage, criticals deal 50% damage + Flat Crit damage.
A Naked FULL STR swordman at 280 has about 730 ATK, it means he will deal 730 more dmage with all spells and attacks.
If you gonna Crit with this much ATK you will deal 1,5K, and you got no weapon in the calculation.
Is i am right Detrone deals 16570 damage at lv5. With 730 Atk deals 17300 damage. With Serpentine Debuff 34600, if it crits 52600 damage. Not considering any equipment.
With a full DEX you will most likely have only 300 base damage. but you will crit for 70% and more times. At this poj t you have to invest in crit damage.
(((((Skill Attack + Effective Attack) + (random(0% … 100%) * Magic Amplification)) * (100% + T0)) - ((Effective Defense * (100% + Level Penalty)) + Elemental Resistance)) * (100% + (0 or 50% if crit)) + (0 or Critical Attack) + Extra Elemental Attack + Enemy Specific Damage) * (100% + T1) * (100% + T2) * (100% + T3) * (100% + Enhance) + Bonus Damage
it means with Detrone, vs a Red Truffle and with Serpetine debuff
(((((16570 + 730) + (0)) * (100% + 17300)) - ((241 * (100% + Level Penalty)) + Elemental Resistance)) * (100% + (0 or 50% if crit)) + (0 or Critical Attack [440]) + Extra Elemental Attack + Enemy Specific Damage) * (100% + 0) * (100% + 0) * (100% + 100%) * (100% + Enhance) + Bonus Damage
Full str
(17300 - 240) (*1,5+ 440 if crit ) * (2 if serpentine)
= 52K~ [it critted]
OR
= 34,6K~ [Not critted]
Full DEX
(16800-240) (*1,5+ 440 if crit ) * (2 if serpentine)
=49K~ [It critted
OR
=33K [Not Critted]
I still prefer FULL DEX with skill with alot of damage.