Looking for the best moving coil cart that is around $5K used

Were you to have a great turntable and the Ikeda 407 tonearm, I would strong recommend  the Ikeda 9TT cartridge. It is second in their lineup but is outstanding with something like the BMC MCCI phono stage.

I've been all over the place on this topic over the past ten years or so.  I started with your opinion - that as long as you had a steady, well set-up turntable as a foundation, the cartridge would be all that really mattered.  I've since come around to realizing that it all matters - the cartridge, the turntable, the set-up, and the phono amplifier (and perhaps the SUT, if needed).

I've heard a VPI Prime at an audio show with a bone stock Denon 103 cartridge - that's a sub $400 MC which, by all estimation, should be like nails on the chalkboard.  It was wonderful, and the turntable brought out it's very best.  Now, that same TT can rise to the occasion if you decide to strap a $4,000 Lyra on its 3D tonearm, too.  Both the TT and cartridge can be made or ruined by the phono amplifier.  Much of the time, those traits that people are really looking for when upgrading their rig - sparkle without harshness up top, a tight, controlled bottom end, and silence in the grooves - are actually achieved through the right phono amplification.  With LOMC, an SUT is really important, too, and they aren't all that expensive in the scheme of things.

For your Pioneer, I'd be tempted to stay in the under $1,000 segments just because there are so many good choices nowadays from the likes of Ortofon, Hana, and the venerable Denon D103 and D103R.  Of course, they'll all sing on your scoutmaster, too.  Consider upgrading the VPI with the upgraded tonearm base and a 3D arm, and maybe a VAS Nova Cartridge (Steve Leung from VAS can probably hook you up with all of the above).

You can find a low hours Lyra Etna on Audiogon for $5K. this one is a Fine Cartridge, you will not be disappointed. Not far from Lyra Atlas and should fit your taste.

Good luck!

@drew_k, From all carts that I own or used to own, all except for one are MC cartridges (Lyra Etna, Dynavector TE Kaitora Rua, Madrigal Carnegie One (by Mark Levinson), Linn Troika, etc., and only $99 Shure M97XE Phono Cartridge is MM and sounds excellent for the price on my TTs. HOWEVER, I do believe that a cartridge makes a huge difference and I agree with you that the sound can be maid or ruined, but for a different reason. The biggest disadvantage with a great and expensive cart might be that you can hear all flaws of the original recording. IMHO, it has nothing to do with a cart, but a master record.