I am going to come down firmly in the camp of "it depends." You are contemplating a 1 year CD versus what? Something like the total bond market index? You don't say more than this is going into your FI allocation: is it a cash/near-cash piece, or just FI as part of a diversified total return portfolio?
If this is meant to be cash/near cash, I think the CD or maybe even a money market fund at VG would be the best choice. You don't want to take too much risk or reach too far for yield with cash.
If this is a part of a longer term FI allocation, I would actually argue for the bond fund. An FI allocation is and always should be about total eturn. With a 1 year CD, we know exactly wat that is: the yield. With a bond fund, you have two sources of potential return: yield and capital appreciation. The latter is important in a number of ugly scenarios where the US economy slides into recession. Given the offset to equities that this part of the FI potential return provides, I think it makes a lot of sense to put the money into something like the total bond market fund.