FDR. My reasons...He led the country through the Great Depression & WWII. His New Deal legislation demonstrated that he was a champion for social justice. His support for formation of the UN & his action in the war re-defined the U.S. role in foreign policy, putting us in a position of power/influence.
Lincoln followed by FDR, then I like Ike. He worked on infrastructrue. Since then no one has had the insight to continue his vision. JFK handles the missle crisis well, I think. Clinton knew how to balance a budget.
Worst? Wilson and Coolidge, although Calvin did have a really good quote "We have lost our reverence for the profession teaching and bestowed it on the profession of acquiring."
If not for the Viet Nam War I would include Lyndon Johnson among the best.
He completed the Apollo mission to the moon, worked to get Congress to pass the Civil Rights Act of 1964, and the Voting Rights Act the following year. He was the first president since U.S. Grant to arrest and prosecute members of the KKK.
LBJ signed Medicare into law and gave the first cards to former President Harry Truman and First Lady Bess Truman. He also signed for Medicaid.
The number of Americans living below the poverty line decreased by nearly half from 23% to 12%. Unemployment decreased.
Not knowing enough about nall former presidents I'll go for Lincoln.