A few quick facts:
1) Future Shop and Best Buy are owned by the same company.
2) Future Shop sales people are paid on commission.
3) Both offer comparable price match guarantees.
So although very similar, I do not enjoy being in Future Shop. Sure, the prices and selection are about the same, but the atmosphere and level of service are subpar at best at Future Shop.
Now, this specific Future Shop isn't too bad. Based on my experiences, this is exclusively due to the service. They are not too aggressive and seem to care a bit more than anywhere else. But this may be due to the Best Buy no more than 100 feet away.
I still find it hard to justify shopping at Future Shop. Especially when a Best Buy is so close. But Future Shop does have some items that Best Buy doesn't, so that may explain the appeal. But beyond that, I'm not sure.