Raptors get a better pure pg who is a better fit for their roster, and Cavs get a PG who would really thrive on a lot more off-ball situations. Mitchell being the primary ballhandler should enable Quickley's game to come a lot easier to him.
Raps;
Garland / Rj / Ingram / Barnes / Potl
Cavs:
Mitchell / Quickley / Hunter / Mobley / Allen