For Jet Boots, the Element you get is not that important since Jet Boot Focus allows you to change it to what is needed, so if you are buying them from the Personal Shops, just go with whatever one is cheaper.
Brissa Set is pretty much what you should try to get since it has really good inherent stats and Set Bonus: if you have a full set equipped, you get +200HP, +10PP, +70 All-Pwr, +12% MEL-Resist, +16% RNG-Resist,+9% All Element Resist, and +50 DEX. A full set of Luther is not that bad as it will give you +120HP, +14PP, +60 All-Pwr, and +9% MEL-/RNG-/TEC-Resist with all three Units equipped, at the expense of ~40 Def per Unit compared to Brissa. All of this is not counting Augments, of course.
You also have the option of Ray Units, as, despite not having a Set Bonus, you do get +150HP, +27PP, +75 All-Pwr, and +6% MEL-/RNG-/TEC-Resist from wearing all three, plus the ability to add (L) Rings to them (once they unlock the option).
And yeah, the Nox JBs are pretty solid until you can get yourself a Slave/Nemesis (I personally use the Sigma since they allow you to get 100% Crit Rate and I can use them as a Fi/Bo, but they are slightly weaker than the Nox).
@ERICK001BC That guide is good, but unfortunately it does not have equipment recommendations for the NA server.