If you want a higher Crit Rate keep Machine Set (The Machine Set has better defense then most of the higher leveled NPC sets so your defense is still high). If you want more HP, Defense, and Crit Damage go with the MG set.
Phoenix's Earrings are good since they boost crit rate, although I'd get better Dura Earrings since you can't really do anything with 100 dura earrings except for use it as crafting material. Tiger Sign is good too since it's one of the few rings that boost crit rate.
Do you have a Mini Robot +4/5? If you don't you should get one. You should also get some Bindis/Stockings.