Favorite phono stage in the $500-$800 range?

Dynavector P-75. It's an excellent value, and low output cartridges are no problem at all. You won't have to worry about upgrading in the future.

Lehmann Blackcube SE

The Jolida JD9 mk ii is right in your price range. This is a tube-buffered phono stage with a great amount of configurability, with separate gain settings for LOMC, HOMC, and MM/MI. It also has a wide range of resistance settings for MC and capacitance settings for MM carts.

There are also some fairly inexpensive tweaks that are drop-in replacements--higher quality 12AX7/5751 tubes and better op-amps--that elevate the performance for low money and no soldering.

I used mine for 3-1/2 years and it's been really good. I only replaced it when I encountered a rare opportunity to get a MAGI Phonomena, which has been compared favorably to the Manley Steelhead.

Check out the Graham Engineering phono stages. I don't know what your cartridge MM vs MC, they make different amps for each. The price is right and I really like their sound. If you have an MM, HOMC,-Mid output cart, the Graham Amp 2 SE is killer good for about $400 new.

Heed Quasar is a little known but outstanding device. I've put it up against well known stages costing much more and it has held its own or bettered the other phono. i just bought a used Rhea which is in a different league. I kept passing on more expensive phonos as the Quasar was just so involving and enjoyable. Looks nice too.