Personally, I'd recommend taking the bus. It'll be about a 15 minute bus ride.
Drive time to the MK Parking lot will be about 5-7 minutes. But then you'll have to wait in line at the Toll Plaza, park your car, take the tram, and then take the Monorail or Ferryboat to the MK. This whole process can take 30-45 minutes.
It should also be noted that the bus drops you off right at the MK itself. Guests parking at the MK Parking (TTC) get held back until 8:45.