Which turntables?

keep 'em all. great tables are becoming fewer and far between in nice condition.

Micro Seki manufactured an earlier version of the Yamaha (1 or 2).

Don't remember the 3.

Do you hear any hunt and peck with the Sony when listening to solo piano?

If not, then it's a keeper.

The only flying saucer Denon's I've used had non standard arms (never heard a stock deck).

I'd keep all three (I have three).

By all means keep the yamaha PX-3, or sell it to me. They are awesome. Linear tracking, heavy platter, automatic, and it does an excellent job playing records. It is one of my favorites. If you want to sell it, please let me know.

The Yamaha PX-3 is a direct drive table from the early 80's.

It is an excellent product as were most of Yamaha's belt and direct drive tables. Although they did not receive the notoriety of the Micro Seikis, Denons, Technics, etc. Yamaha's tables were well designed/built. I owned a couple and the YP-701 is one of my personal all time favs.

If in good condition, I would give the PX-3 serious consideration.

IMO

The Sony PS-8750 is a real winner as long as the motor is speed stable (Dekay's test is the one I would do). The other two are good tables as well. FWIW, I find that the big brothers of the PX-3 don't deal terribly well with low compliance carts (so, jumping to conclusions as I am sometimes wont to do, I expect the PX-3 wouldn't either).