I’d say you already have a really good setup which fits together. There seems to be no component with a certain weakness within the chain. Motor is already separate, I assume your arm is already fully adjustable. Although a better motor unit always improves, especially a better arm…I wouldn’t modify this combination to be honest as you have to be sure about really better synergy then. The new component you’d buy would be above the rest and implicate further changes.
I think you’d have to switch the whole thing to noticeably step up.
A better arm will probably be most noticeable (Kuzma seem to be great as some others). I’d take arms with a fast transfer speed (metal done right, no wood parts or similar).
The next big step imo would be a high mass table with low weight (or better no weight) on the spindle. This means magnet or air bearing which is expensive. And soft isolation down to 4 or even better 2 Hz. This means none of the usual accessories but either something designed like that within the turntable (rare) or a very good passive or active isolation platform (3-15k).
You can buy extremely expensive concepts not providing all this, which I wouldn’t do.
An even better cartridge certainly also helps but I’d do the rest first.
So if you’re after bigger changes, I’d wait until you can buy a new table and tonearm together first.