I'll put up a Harrison M300 against any American iron.
IMO the best bang for the buck is the Grizzly. It is a MODERN lathe in that it has rolling element bearings in the headstock, and has a D-1 mounting chuck rather than threaded.
The South Bend 10 and Heavy 10 are relics. They're hard to work with and aren't accurate enough. Not anymore.
I would only consider lathes that have the following features:
D1 Camlock mounting
MT 5 in the spindle
12 inch swing
30 inch between centers
Free standing (not a bench lathe)
Geared head
Quick change feeds/threads
Foot brake for safety.
You won't find these on American iron that you can afford.
I'm as patriotic as the next person, but the reality is that in machine tools as in cars better values can be had with imports.