the mech rings and the MDI rings without sockets the mech rings are way stronger in stam, vers, haste etc imo by a landslide
mech rings that proc one socket ea would be 6 str vs MDI rings with 2 sockets at 12 str when gemmed
you would have to decide 6 str vs all the extra secondary stats mech rings have which also add more power to attacks and survival
do both and you are covered