You are fortunate to live in missisauga as I understand there is alot of airsoft happening all around you!
Welcome to ASC
If you are 18 the first thing you need to do it get age verified. This will allow you access to the classifieds where you can purchase your airsoft guns.
the best rifle is a very very strange question as it doesnt have an answer really....
i would classify rifles more by quality rather than model.
look for something like tokyo marui/classic army/g&g or anything of the likes.
after you find a good deal on a quality gun then start selecting what gun model you want (mp5,m4,aug, p90, etc)