Off-brand wax is terrible compared to Scentsy. It doesn't last as long, the smell isn't strong, and you don't have a very wide variety of choices. That's why it's so cheap. You kind of get what you pay for with this kind of stuff.
I have a Scentsy warmer and have used the Walmart Better Homes wax in it and counldn't really tell a difference between the two. I prefer the Walmart wax over Secentsy's for the simple fact that they are $2.00 and you don;t have to order them you can just go buy them at the store.