Upgrade Rega Exact2 on built-in SUGDEN A21aiS2 Ph

I am using SUGDEN A21aiS2 AMP and built-in MM/MC Phono stage and REGA RP6 with Exact2 MM.
Could you let me know your opinion about upgrade from Rega Exact2 MM Cartridge, please?
How about NAGAOKA MP200/300?
At least for the acoustic music I listen to, I doubt if MP-200
can be beat at that price point.And I've owned at least a hundred carts in the last 40 years. Definite upgrade from Exact . I doubt 300 is much better.
Dear Schubert.
Thank you for the information.
Please let me know what cartridge you recommend?
My budget is around $500.