Things I can note off hand is getting +2 Legs, Body, and Head. The extra benefit from Cureskin on +2 body and 2mp/tick refresh is very nice. +2 Head will give you 3% more potency and is fairly simple to assemble a pop set for the boss with the hardest part of the pop building process being Tunga. The extra % conversion of the pants as +2 goes a long way to making WHM efficient on cures and I would personally prioritize that piece over the other two pieces - but in the end, all three are equally as important and decently simple to build for.
Keep in mind that the latent effect for
medicine ring only activates when you're in yellow HP. That isn't hard to do in Abyssea, but outside you may have issues with that unless you want to invest somewhat heavily into a latent set.
A good compliment to the
Sirona's ring that was mentioned earlier is the
ephedra ring. For straight up cures, skill is very important now.
The WHM empyrean neck that was mentioned earlier by Itze is also a good piece and I'd recommend it too.
If you're looking for straight up MND pieces for the cheap to build a MND set as well, consider looking up
Kaikias' cape and
ajari bead necklace. Both are fairly common and cheap to come by.
aredan earring is another nice piece to have for MND as well that is fairly low on the AH. The three items I mentioned in this paragraph comes up to a grand total of about 50K on Ragnarok ATM.
In the end, it depends on how many sets you want and what you want to build for. If you're looking for a straight up Cure mule with nothing else, prioritize the AF pieces listed above, cap out potency (50%), and than stack skill for all it's worth and go from there.