Those are fundamentally different things. Discover has a like 2% interest savings account, which is decent, guaranteed and FDIC insured. Highest interest savings right now I believe is CIT at like 2.4%
Wealthfront is a system for spreading money across investments, like stocks and bonds. The returns are whatever the assets do, which could be 15% or it could be negative depending on what the market does, and it takes a sec to get the money out, since they have to liquidate your positions
It depends on your risk tolerance, how long the money is going to sit there, and how much you want to be exposed to the market. Probably do both in some amount.