Upgrade: Turntable or Cartridge?

I currently own an early generation of the Clearaudio Emotion turntable (no CMB, spiked feet, aluminum Satisfy tonearm). My cartridge is a Grado Sonata1 (new version) Reference (High Output). I'm trying to decide if I should upgrade the turntable or the cartridge, and between the two, which would provide the greatest benefit. My phono stage is the PS Audio GCPH, which I've found to perform pretty darn well, and don't think I need to upgrade that at the moment.

I do feel that the Emotion turntable could still handle a cart a good deal more expensive than the Sonata1. To my ears, the table is extremely quiet, with fairly decent speed stability. There are a few convenience things that are annoying, such as the decoupled motor which always ends up sitting against the table and needs to be moved. The location of the switch to turn the power on, and also the exposed belt can get annoying. However, I'm still willing to live with those things if upgrading the cartridge will provide much benefit. In the end, I'm in this for the sound, not the convenience, otherwise I wouldn't have a turntable.

For cartridges, I was considering quite a range: Shelter 501 Mk II, Benz Ace or Glider, Clearaudio Concept MC, Ortofon 2M Black, Dynavector 20X2 or Karat, etc. I'd like to try out a decent MC for once, if I do choose to upgrade the cart. I've had trouble getting rid of inner grove distortion with the Sonata1 and Satisfy tonearm, even after very careful alignment. Maybe they aren't a perfect match?

Any ideas here?

Thanks