Sent Back the Pro-ject Turntable: What would be the best option in the $1800 range?

It would be only fair to point out to kimt that all 3 cartridges on your list, Chakster, would be at least 30 or more years old at this point in time.  To find an NOS one would be serendipitous for sure, but also one would be taking a chance on the condition of the suspension of such a cartridge, which would be expected to have deteriorated, even if NOS. In fact, it's certain that any sample of any of those 3 cartridges will have "changed" sonically since the date of its manufacture. This change could be OK or more likely not OK.  While I share your admiration for those 3 cartridges, and I own them all, I suspect there are many modern cartridges, recently manufactured, and in the same price range, which would be less risky to invest in.  For examples: Nagaoka, Audio Technica, etc.

To the OP, if indeed the SL1500 has the very same coreless motor as does the SL1200, and if the $ are very important to you, then go for the SL1500.  Thanks to Rego for the cogent information, and I apologize for misinforming you that the SL1500 lacks the coreless motor, albeit, I still think the SL1200 will be better sonically, overall.

Mijo, Please stop dispensing your beliefs and opinions as fact.  The AR XA is a primitive effort, a piece of junk by modern standards, although a standard bearer for its time (which was 60 years ago).  It bears no comparison to any of the new crop of Technics DD turntables, IN MY OPINION.  It doesn't hold a candle even to my 40-year-old Denon DP80.

Torque is not a big deal, once the turntable is up to speed, but the SL12010GR is just a much better product on all levels (motor, electronics, platter, plinth, etc), compared to the 1500.  I would add my voice to the chorus: go for the GR.