Some schools are better than the others when it comes to different disciplines in engineering. Like Waterloo for example is a very good school for software engineering. I would usually tell people to go to both schools and compare campuses, but since you already did that and you liked both, it's up to you. I mean if i were you and i lived in Hamilton, i would choose mac to save on commute and other living expenses. If you live far from both and you are gonna live away from home, then take a look at other comparison points.
McMaster engineering is really unique and different from some universities because we have 3 unique combinations to go with your engineering degree:
1) Engineering and Society
2) Engineering and Management
3) Engineering and International Studies
I don't know about Queen's, but these programs are very unique in nature and not many universities offer them.
In case you decide to go to mac, here are your first year courses:
Ohh and here are some cool mac eng videos: