MM cart. Recommendation

I have an Oracle Alexandria with Sonus Formula IV tone arm and a Graham Slee Gram Amp 2 SE. I am presently using a Sumiko Pearl Cartridge and am looking to improve. Nothing lacking but I figure there must be better. The 44db of gain in the Graham Slee keeps me in the MM or HO MC camps.
Grado cartridges seem to be my best choice from looking through the archivves but am open to suggestions.
Budget could extend to the $300.

Thanks