STR/VIT mix and match is the cheap option. Ruby/Topaz/Platinum is the expensive option. Just depends on how much gil you're willing to spend to play your job as optimal as possible, but really there isn't much else to spend gil on outside of vanity.

SS is valued higher than Det until you reach the point where you can hit the 9GCD zerk. Optimally your Ragnarok should be melded with Crit/Det or Det/Acc or Crit/Det/Acc and then getting the SS from your accessories. If you can't manage this, then melding SS on your axe is an option and not a terrible one by any means.