What did people like about president Lincoln?

Lincoln opposed the spread of slavery to the territories

Explanation:

His Emancipation Proclamation paved the way for slavery's abolition. Lincoln issued a preliminary Emancipation Proclamation, which took effect on January 1, 1863, and freed all of the slaves in the rebellious states not under federal control, but left those in the border states. He came to see emancipation as one of his greatest achievements, and would argue for the passage of a constitutional amendment outlawing slavery (eventually passed as the 13th Amendment after his death in 1865).

People have a way of making a legend out of people who are assassinated.

Much like Lincoln he was portrayed as a country bumpkin and turned it to his advantage. Harry Truman also was from the people. Like Lincoln he owed his political office to political bosses but didn't let them influence him as president.