Moving coil VS moving magnet/iron

No arguement lewm. It is a subjective matter but when it comes down to the scientific details I like to see a fair and even presentation. When I see a skewed one my BS antenna goes up.
I guess I am lucky. Currently my least expensive cartridge is the Ortofon Windfeld Ti. I have not evaluated cartridges at the lower end of the price range in a while. The Last one was the Ortofon 2M Black which I have to admit was excellent. There is certainly a point of extremely diminishing returns and that point (I'm guessing) is about $1K . I can certainly say that a Clearaudio Goldfinger is in no way $10,000 better than the Windfeld Ti.
It is all about what you can afford and what you like the sound of. The problem is that auditioning cartridges is difficult and many of us have bought cartridges we wind up not liking. 

I have on hand a Koetsu Urushi, ZYX UNiverse (1st version), Ortofon MC7500, Ortofon MC2000, Audio Technica ART7, and Dynavector 17D3.  The UNI, MC2000, and ART7 are my current favorite MCs, but they are not always preferred to my Acutex LPM320, B&O MMC1, Stanton 981LZS, or even my SS re-tipped Grace Ruby.  Some days I think it has as much to do with the state of my ears as to the cartridge, tonearm, turntable combo.

I never held on to cartridges I didn't think I would use any more. Fortunately, the urge to buy another one has not struck yet. 
Your ears are rather simple devices. It is actually the state of your mind. Your psychological state changes the way you perceive, pain , hearing , sight, all of it. In other words, one day you are in the mood for this another for that. It is always nice to have a choice:)

Yes, "ears" was used by me as a metaphor for all the other stuff you list.

@cakyol, since you'll probably want a better phono stage to exploit the qualities of good MC, I'd suggest upgrading that first.
You may find that the cartridges you have are perfectly satisfying.
FWIW I didn't like the AT OC9 at all, too lean and soulless.