Wow I listened to my old AR ES1 last night

Welcome back to analog! From a quick view of the classifieds, there's a Basis 2001/Rega/Benz Glider for sale for $2500, and Well-Tempered Classics are always available, it seems; as far as new goes, the Michell tables are indeed nice, and for a lower price you could get an MMF-7 complete with arm and cartridge and still have a lot left over for records. I've heard all of these and would say that they all should be an improvement on the AR in absolute sonic terms, although you may find you like the colorations of the AR (which was a pretty good table in its time) enough to stay with it--by this I mean that the better the turntable/arm combination, the more neutral the sound, and while you'll be getting more information sometimes you lose some colorations (like a mid-bass bump) which you may find pleasing and may have masked some deficiencies in your records themselves. Ultimately I'm very glad at the upgrades I've made over the years (particularly as my tastes turned to classical recordings), but I do note that some of the older rock records I liked from the 60's just don't sound as good as I remember them (Ah, nostalgia just isn't what it used to be!), and that is likely attributable to the less neutral sound of my older turntables. See if you can audition any of the ones you are interested in with your own records. Good luck!