Turntable parts upgrade

I recently got back into vinyl after a 30+ year hiatus and now I am hooked. I had forgotten how great vinyl sounds. Last summer I picked up a demo VPI Prime scout from a local dealer with the upgraded WH40 feet and a Ortofon Quintet Blue cart. The unit was their in store demo and had approx 20 to 30 hours on it. I love it and I am enjoying vinyl, so much that I hardly want to listen to digital anymore. I am slowly expanding my vinyl collection. Seeing how much I love this and what I am investing in my vinyl collection it makes me ask the questions: If I were to upgrade something on my TT what would make the most impact? I understand the Prime Scout base is a solid base to start with, so would next step be to upgrade to a better cartridge? Or upgrade to one of their better 3D arms? Or don't bother upgrading arms because I can mover up to a Prime for a little more which has the better arm and larger platter? Cartridges I was think about were Hana ML or Quintet Black. 

For reference the rest of my system is: PrimaLuna EVO 400 integrated, Sonus Faber Sonetto VIII, Sutherland Insight with the LPS. Digital is Chord Qutest, Innuos Zenith mkIII. All cables by Purist Audio Venustas and Corvus. 

I know thats a lot of questions but just trying to get an idea what makes the impact with analog upgrade in the chain. My last TT was probably a basic $150 Technics when I was a teenager in the 80's, so this is my first high end TT.

Thanks