https://forum.audiogon.com/discussions/audio-technica-at-art9-phono-cartridge
+10 for Audio Technica ART9 (art9xi appears to be replacement, though lpgear.com days art9 is the flagship above the xi).
Read the comments in the audiogon thread attached above. The only two things necessary to know with this cartridge is proper setup (similar to all micro-line stylus) and break-in. The latter takes anywhere between 50-150 depending on who you ask. In the interim it’s still really really good but it does come into its own after that time period.
I have never read so much about a cartridge without a negative review. Again, the cartridge needs proper setup and break-in.
I found phono stage compatibility to be critical regardless of cartridge. Without playing the cartridge of your choice with your Luxman you’ll never know how your upgrade cartridge is going to sound. Each phono stage greatly affects the sound.
I also want to comment on what @mijostyn said about what one will need to spend on a mc to improve on a mm/mi cartridge. First, it's about what your ear hears. Second, it's what your ear hears in your system. @mijostyn has neither your ear nor your system. I'm sure with his ear and his system that his experience is true. His comment about the high and low level phono stages mirrors my thoughts above. Your phono stage may accomplish both levels well or not. Finally, many people will tell you that a $700 dynavector 10x5 will blow doors off of any comparably priced mm. It's a high output mc that does sound amazing. Similarly, I doubt anyone has heard a mm that sounds anything like a koetsu rosewood...smooth as silk. It all comes down to opinions and when it comes to aural opinions, you can only hang your hat on yours.
Goodluck in your search. If you can, find other people with your Luxman who listen to vinyl...even, better with a VPI. I’m sure they’re out there.