I have had great experiences with Audio Research over the past several years. I’ve always been curious about Conrad Johnson but haven’t ever heard any of their products.
While the recommendations of an LS28 or REF 6 are great they don’t seem realistic for you since you were hoping to stay around $2k.
For that budget, I believe the LS 17SE would be a good move. There is actually one on USAM now that has been there for about 3 months. Asking 2100 and I bet you could get it for around 1800. While I never had that model, it has maintained a great reputation and will not likely ever go below that value for one in good condition.
If you fall in love with it, then maybe you can go all the way up to a REF 6 next. They are quite impressive and can be found for about $7000. I think they are the sweet spot for value right now. The REF 3 are around $4000 and pretty outdated. The REF 5SE still bring around $5500 so for the extra you can get the latest design and modern aesthetics. Again, I doubt the value of a REF 6 will ever drop that much.
Good luck!