When I moved from MM I opted for the Denon DL103 - even though it has a sperical stylus it was noticebly better and very affordable
Then after reading about the ZU version (and similar approaches) I applied my DIY mind to the problem and epoxied a brass plate to the cardridge, which again improved things, because
- it added some mss, which suited my Rega arm better
- it tightened up the sound - much crisper with a tighter bass
The final upgrade was to replace the stylus with a Soundsmith mod to ruby cantilever with an optimized Countor contact line stylus, which improved the details amazingly
Now I am not suggesting you go thruogh the same steps, but the things that make a difference are
- stylus profile and cantilever material
- Matching the tonearm
BTW - I had a Rega cartridge and by comparison it was muddy and lifeless
@jasonbourne71 recommendation is pretty good by all accounts, but also look at the Denon range (not necessarily the 103).
Audio Tecnichnica also have some MM carts that may improve things also
Hope that helps - Steve