Who got the better end in the Compromise of 1850?

The North.

For this reason, Congress had tried to make a big gesture of appeasement to the South in the form of the Fugitive Slave Act - cracking-down on runaways.

This backfired badly, and 'Uncle Tom's Cabin' was written as a protest against it. The best-selling book caused a new spread of Abolitionist feeling in the North.