We have been through a lot of Math curricula, in the quest for just the right one. Saxon was by far my favorite once I discovered it while doing 2nd grade, and we continued it into 3rd.
The consumable textbook made it really easy for my daughter to do the work. Saxon also covers so much more than standard curricula, including pre-algebra skills, square roots, and both English and metric measurements. I also liked that it constantly reviews, and reinforces, concepts that they have already learned.
I will warn you though, that the format completely changes from 3rd grade to 4th. It becomes more of a standard textbook, which is not really what I was personally looking for.