Like what storm rider said.
Critical Attack stat and 1 point per str <<<<< ( the one you get from items.)
This is also know as True damage.
When you strike a critical (There will always be a total mod of 1.5x after defense reduction damage) then critical attack stat is added after it
Current as of R7 we all came to agree that STR is better at the edge as the skill damage is significantly lower.
Once R8 hit pretty much for Strength build to win a Dex build your invest of total damage must be > than Critical Mod (aka 1.5 of total damage). This is free for dex builds since Critical formula is a betch.
Until there is additional āspecific scaling to strengthā which currently there isnāt any sadly.
R7 = Str is generally better.
R8 = Dex wins in damage over time in a span of 3 minutes rotation.
Str builds are still decent just that, donāt expect to win a dex build over time lasted duration.
So in short
STR at R8 = Start out with a BOOM then constant pace without much explosion. Starts out at a good rate. Goes up slowly Constantly have small budge from random crits 10-30% in this case
Dex at R8 = Start out with small explosion and constant small explosion after it. Which is pretty much linear spiking up this way.
Graph for reference

Currently there are a few ways which can bring back stats build diversity again.
New crit accessories that gives us way higher crit rate. (like 120 crit each piece)
Implement a new system that add additional awakening stats such as crit rate.
Change and revamp of the stats structure itself where STR can add crit rate for swordsman and DEX does add minimal damage/maximum damgae lesser than str in compensation.
A total revamp of offensive and defensive skills to give % scaling. So this will make both STR + DEX equally important
It will become a free form.
HIGHLY NOTE this graph does not apply to fencer. Reason being Epee Garde exist.
When you have a additional 50% inclusive of Epee the spike is ridiculously to the point that making anyone who does not invest in crit rate losing so much damage overall.