Shootsoft is grossly overpriced on many of their guns (you can find the identical product for 1/2 the price elsewhere) and will rape your ass on shipping.
Buyairsoft.ca has a rather poor reputation for selling shoddy products and having poor customer support in terms of communication. That being said, I've dealt with them before for pellet guns, and never had a problem
007 has the highest grade of guns out of all these dealers. I don't know how they are now, but I tried many times to contact them for guns, I never got replies. It was a very frustrating experience that left me doubtful if I'll ever try again. Although many people on this site swear by them and have had great service.
I can't vouch for the others as I've never dealth with them personally.
The best option is if you're 18+, get age verified and you'll have access to these and many more retailers in the classifieds, as well as access to quality used guns at decent prices.
If you're not 18, then you're out of luck, as you shouldn't be owning airsoft in the first place.