I have an Oreck. It is lightweight, has a bag and picks up like a wonder. I have a German Shepherd (I used to have two) who sheds year round but blows her coat twice a year. This is the only vacuum that has been able to keep up. Also, I have severe allergies and I find that having a bag is much better.
I know it is hard to spend alot on a vacuum but it really is worth it to spend the money. I use mine more than once a day and it has definitely paid for itself.