MM or HO MC Cartridge Choice-Input Please

My best bets for new cartridges in this area are

Jico Seto Hori 

and

Acoustical Systems Fideles

While Linn is a company that elicits strong emotions from people in this hobby, I think there is a lot of value in their analog hierarchy. Table is the cornerstone of the analog system, then tone arm, and finally cartridge. I would add a corollary and put the phono stage right after tone arm, and once everything else is right then commit fully to the cartridge.

It is my experience you get a higher level of reproduction using something like one of the new Audio Technica OC9 cartridges or perhaps the ART9 on a fundamentally superior table and phono stage over a $2000 or more cartridge on a less capable turntable and arm.

Since you are using the onboard Shindo MM phono stage then a SUT makes the most sense. Mike Sanders has been building quality gear for decades, I would expect his selection of transformers for his step up would be quality pieces. Start with what you own in that area, make a meaningful upgrade in turntable, and once that is complete then select the level of cartridge you can afford.

I had a Rega P5-the next step up from the P3.

Save yourself the hassle stay with the  Rega philosophy. That means simple. Get a Rega cartridge. 3 screws,set tracking force-done

If your MC curious, then look at the Ania. Exact for MM

While any of those carts will sound nice, it is hit or miss, since you will also need to shim for VTA(if that's what you want to do). 

Get a different table with adjustability if you want to really explore cartridges.

In my accumulated experience, MM outperforms HOMC. Also it’s a good idea to define HOMC. I would define that group as having an output >> 1.0mV at standard velocity. An AT ART9, for example, is not an HOMC type.