I called almost everyone from a-z and they were either too busy to come for an estimate (within a week) or too busy to come and cut the tree (within 4 weeks). The Stouffville Tree Service guys are insured, but they aren't arborists. They are also substantially cheaper, efficient, and honest. Told me that they would come Monday morning and I woke up this morning to a tree that was being cut down. Our Silver Maple was loved, but sick, rotting from the inside, and structurally unsound... I was worried about how it would come down since it seemed all tangled with the another tree, but they did a great job.
Their price is the best amongst 4 estimates. They informed us that we had to get permit from the city as well as agreement by the neighbors. The contractors came on time and cut the trees professionally and cleaned up the yard afterwords.