Any experience with these turntables?

You're comparing very old tables in unknown condition and expecting anyone to know. Which might have been a reasonable question if asked back in the day when they were all new. But now, condition is everything. The best of the three when new could easily be the worst of the three now, depending entirely on condition. 

The smart thing to do is hook them all up play a record and see. It takes like 5 minutes to swap the same cartridge, no point perfecting alignment you won't need it not for this.

Otherwise, the Sansui is the safe bet. Mint condition matters most. Auto off switch you can do without, all it means is you have a manual instead of semi-auto. You have to cue it up at the end. Big deal. 

But they're all turntables. Ultimately you go with the one you like the one with the look and the feel as well as the sound. So which one do you like?

Millercarbon

Great advice! I think my buddy would let me take them home and try them. Maybe I can borrow one of his cartridges that fits on all of them too.

That’s the best way. Here’s the full-blown methodical way. One by one check them out visually and by hand. Pull platters, check belt or idler wheel for condition- cracks, dents etc. Turn bearing by hand, feel for smoothness and play. Do the same for the arms. Set the arm to balance at zero skating and without cartridge and check to see how freely it floats. If it sticks at all that’s not good. Or if there is any play at all also bad. Check suspension and feet. Look for hidden damage. One little jammed spring or bushing can ruin performance. Phono lead, cartridge pins and wires. All these things can turn into major headaches later. Mount the cartridge and don’t fuss being precise it won’t be worth it. Listen for music and also listen for background noise like bearing rumble. Differences I bet will not be subtle and one will stand out and it might not be the one we think right now (Sansui). AR has no mat but if another one does swap it over to AR.

I have a vintage 1976 Technics and can tell you any or all when they get that old the bearing can run dry and just need lube. Which is why checking that is one of the first steps. Hopefully your guy being into it has taken care of some of the more obvious stuff like this but it pays to be thorough.

If one stands out you’re done and can get to tweaking starting with better cartridge alignment. But if you find two that are close then take a closer look at the parts and what can be improved or needs improvement. You will find there is a huge difference between the sound you get initially and what you can get with just a little time and effort tweaking these things. You learn a lot and all of it directly applicable to every other analog rig you can name. Most guys never mess around, too scared they might damage their Precious. These no worries so make the most of it.