Based on my own experience with the VPI "HW" series turntables, I suggest you begin by upgrading to the HW-19 Mk 4 version. The heavier platter and new suspension springs make a noticeable improvement in performance, which in turns makes a better platform for a higher quality tonearm. If you get the "Mk 4" upgrade package, you will also need to buy the thicker acrylic "Super" armboard, to compensate for the increased height of the platter. When I upgraded my "Mk 3" to the "Mk 4" version, I was very pleased with the substantial improvement in performance. Shortly after making the upgrade, I bought a Rega RB-900, which proved to be an excellent combination with the "Mk 4" turntable.
A used Rega RB-900 is a fine value, as is the VPI JMW 10.5 (used) or JWM 10.0.
A used Rega RB-900 is a fine value, as is the VPI JMW 10.5 (used) or JWM 10.0.