I like Alex Smith rest of season based on how the Lions looked in game 1, but Stafford almost certainly has the higher ceiling. I've always liked Alex Smith for his consistency, but he is almost never going to give you huge numbers.
I think Stafford and the lions will bounce back, and, they've proven that their defense isn't very good, so good game scripts should be plenty Stafford. Depending on how many teams are in your league, you may be able to pick up Smith off waivers later if you want.. Thanks.