Oktava's quality control is poor, although I think the MC-012's
are better made than the 319's and 219's.
Personally, I like the one you have over the other two generally.
If you have a boom style mic stand, raise the microphone to the
singer's forehead level, with it pointing towards their mouth.
I'm assuming you're using a mesh pop screen also BTW.
Try it that way and hear how you like the sound or not.
That Oktava is on somewhat on the dark side

of neutral.
If you like an unhyped sound like that, you'd want to consider
the Studio Projects B1, which is a bit brighter than a MC-012,
yet still pretty neutral.
Small diaphram condensers are prone to popping when close miking, however, with careful postioning you can get a good recorded sound.
Chris