I am also a knife user because that speed is brilliant, and all you need for the low-health early wave stuff. I keep both early on though, because of flavour. The crovel has a bit more range, has a knockdown/more protective version of bash, feels a bit like an axe and has a blunt alternate attack which is very satisfying to use when it knocks an enemy across the room into a wall!
Best use for it for me is that knockdown bash, the ability to parry a bunch more stuff and (like the knife) horizontal swings at head level for a bunch of kills per swing!