Best weapon potential? 21% of stats vs 15% of stats

I know there isn't really an answer of what the best potential for a weapon is, as it comes down to preference but I'm really wondering what route I should take for my current weapon. I'm not really into bossing too much, I'd rather have a potential for everything.

My current my potential is 6% all, 9% attack, and 6% total damage. My question is this: Is 15% total damage better than that potential and if it is, WHY?

I'm hitting more than I've ever hit before, and I know it must be the 6% total damage, at least I'm guessing it is. Can 9% atk and 6% all really match 9% total damage more?

Thanks for your help, it's always appreciated!