A best all-around vintage TT would be one that I'd consider serviceable, parts available, reliable, and sounds good to boot.
This would be a small list:
AR-XA/XB/Etc.
Linn
Thorens TD-124
Thorens 160 series and close relatives
Thorens 125 series and close relatives
Systemdek (semi-vintage)
Ariston (semi-vintage)
Rega (preferably P2, or better, P3 and up)
Perhaps the VPI scout (semi-vintage)
and of course, the ubiquitous Technics SL1200MK2.
I may have missed a few.
All the above have parts availability via either factory support or aftermarket support, are relatively durable, easy or somewhat easy to repair, perform and sound well, and readily to somewhat readily available.
This doesn't make these the best sounding, or most collectable, and none are perfect, but it's a good, all-around and safe bet.
Now, each model mentioned will have some strengths and weaknesses, so pick accordingly to your needs.