It kind of depends. Wendell Willkie against FDR, hell no. Wendell Willkie against Bill Clinton, yes.
Exactly my opinion.
So Wendell Willkie, without any doubt. He would have been a great president. I would vote for him against any Democrat in 1940 except FDR.
The rest:
1900:
✓ Teddy is on the ticket
1904:
✓ Teddy has my vote
1908:
✖1912:
✖ Teddy yes, Taft no
1916:
✖ Hughes is okey, but Wilson is my first choice
1920:
✖1924:
✖1928:
✖1932:
✖1936:
✖ Alf is ok, but no chance I vote for him against FDR
1940:
✖ only with FDR as Democratic candidate, otherwise enthusiasticlly Willkie
1944:
✖ Dewey is ok, but no chance aginst FDR
1948:
✖ No, I love Truman
1952:
✓ Ike is great
1956:
✓1960:
✖ but only, because LBJ is on the ticket
1964:
✖ hell no, Goldwater is the last candidate, I would vote for
1968:
✖1972:
✖ 1976:
✓ Yeah, Gerald Ford was a good president and deserved an election in is own right. I prefer him over Carter
1980:
✖ Reagan? Never ever
1984:
✖1988:
✖1992:
✖1996:
✖2000:
✖2004:
✖2008:
✖2012:
✖