When you buy a dslr, you don't buy just a body and a kit lens but you buy into a system.
Canon is far better than Sony in this regard. Sony's OEM lenses are pretty expensive, and third party lenses and accessories are relatively limited.
Canon on the other hand has a wide range of offerings in terms of both price and capability, all the way from consumer zooms to pro level super telephoto primes and most of these are relatively easily available. The used lenses/accessories market for canon is also better than that of sony. So, in the long term, Canon is easily the better choice as a system.