In answer to your question, would the dog really be that much better off? In both places they are "housed" - one in a cage, the other in your yard/room. In both places they would be alone for a large percentage of the day and prone to being bored/destructive. We've all walked past the shelter cages and seen the dogs barking/yelling/tearing up blankies because they have nothing to do.
In a shelter they have the option of being adopted by people who have the time to spend with them.
I've had my share of dogs, and whilst the girls sometimes ask for a new doggy (they still miss good ol' Tassie Jim) I have explained to them that with our lifestyle (house is empty 5 days a week from 8.30am - 4pm and most weekends) it is not fair on the dog to be left alone for so long.
Plus, if you are going to be out most of the day be it for work or whatever, how long will it be before you start to resent having to come home, walk the dog, play with the dog, clean up after the dog, in between taking care of kids and other family things.
A dog is a huge commitment, as is any pet and I would strongly advise you to think long and hard. If you do decide to take one, think how hard it would be for the dog if you had to return him/her/it after say 3 months because things just didn't work?
Just my lil ol' opinion.....