I'd get the mini Luna. Most go for the noir because it's black and pretty but they are just the blue+blue mini luna combo (the heavier balls). I thought about getting the luna noir, but I like the variety offered by the mini luna.
I love my Teneo Duos but they're pretty large, if you're pretty small down there, they probably won't be comfortable for you. I've heard nothing but good about the Luna beads though, they look great if the Teneos are too big for you.
As long as you stick to good materials, any will be okay. I have smartballs and thought they were fun but not particularly good kegel exercisors. I have heard good things about luna beads, though also as a fun rather than serious buy.