Base DEX

It doesn't matter if you hit less than someone with lower dex than you if you still kill what you train on in the same number of hits as them

Of course, if it takes you 1 or more hits than someone else, THEN there's room for improvement

As a BW WK, there's a very large opportunity for that kind of thing. I currently kill Blue Wyverns in 3~10 hits or so, any extra str/atk helps reduce the chance of the higher numbers.

On stuff with lower hp (eg. Dual Pirates - I 2-5 hit KO them) it would take a lot more to improve - I'd need ~28 w.atk to get my max down to 4 hits. Extra damage still helps my chances of doing those 2-4 hit KOs, though.