They are both pretty equal in general, just for different reasons. Kratos has the amazing AP generation and easy to use square mashing style, raiden has the fantastic supers that are easy to combo.
A bad kratos player will still get high AP and will just miss with supers a lot. They will most likely have so many chances to use those supers because of the high AP that they'll get at least a few lucky kills and place often enough. A good kratos will still have high ap generation and also be able to aim his supers properly, getting him great kill counts
A bad raiden player will have moderate ap generation and get a decent amount of kills off the supers because they are just that good. Might not win, but will place. Good raiden player will combo the hell out of people, build nice ap and time perfect supers. Often getting double to triple kills off his lvl 1s alone.
In a 1v1 raiden will do great, in an FFA where kratos can hit groups he's amazing. But raiden also does great in FFA. It's a toss up