Budget?
On phono stages…since you have ARC pre and amp, seek out a used ARC phono stage. I had MoFi UltraPhono and it was ok. Not bad not very good either.
I upgraded to Sutherland KC Vibe mkii then went up the Sutherland line to 20/20 MkII with LPS
On cartridges…I haven’t tried a ton of different MCs but used Hana EL on Rega P2. Then upgraded table to MoFi UltraDeck then upgraded cartridge to Hana ML. Both the EL and ML are very good. The ML is in a different league though.
One downside with the Rega P2 for me was the lack of capability to do VTA adjustments. And that was one of the main reasons why I moved away from Rega tables.