Some people do not like refurbished cameras, they feel that the odds of more trouble are high. The refurbished Canon cameras do not have a full one year warranty, they have a 90 day warranty. Used cameras have no warranty at all, so unless you know or trust the seller, there is a elevated level of risk.
Also realize that most used camera buyers are not aware of the Canon refurb camera program or do not have a broken camera to trade in.
Its your money, take your choice.