Final answer:
The biggest mistake by the founding fathers was avoiding the issue of slavery, which sowed seeds of future conflict. The Great Compromise, however, was a wise decision that helped balance representation in Congress and was pivotal in establishing the federal government.
Step-by-step explanation:
Regarding the compromises made by the founding fathers, opinions on the biggest mistake and the best decision can vary. However, many historians argue that one of their most significant mistakes was the series of compromises that sidestepped the issue of slavery, such as the Three-Fifths Compromise and the decision not to set slavery on a path towards extinction. This inaction led to constitutional protections for slavery and set the stage for future conflicts leading up to the Civil War.
On the other hand, one of the wisest decisions the founding fathers made was the Great Compromise, which balanced the needs of both large and small states by creating a bicameral Congress with the House of Representatives based on population and the Senate providing equal representation for every state. This decision was pivotal in ratifying the Constitution and establishing the federal government.