This is just to share my good experiences with my modded RB-250 (Origin Live), and several MC cartridges. These have worked very well for me, and are all part of my cartridge collection: Ortofon Jubilee, Dynavector Karat 17D3, Audio Technica OC9ML-II.
The tonearm is good enough to let the listener know the character of each of these units. The Jubilee sounds solid, strong, neutral, well extended (bottom to top), and easy tracking of anything.
The Karat 17D3 is the most neutral of the three, with a smooth extended and seemingly infinite treble. Never, ever offensive. VERY good tracker, but not as much as the other two.
The OC-9ML-II is the very best tracker of the three...will take any hot LP in stride, and not break a sweat! It also shows a slight, small, treble emphasis which you may (or may not) like.
All three of them show ample stage width, depth and height. The images within the stage are rather explicit, and I could not prefer one over the other in this criterion. My main point of difference is in the tonal presentation, which is the most neutral in the Karat 17D3.
I understand that the Dynavector entry-level model, with the red body, is very well liked, but have not heard it.
One MM unit which I like rather well on the modded RB-250 is the Ortofon Super OM-20.
Happy Hunting to you.