Kellen sounds like "I want to honour a
Kelly but it's too boring so I'm going with Kellen". Needless to say, not my cup of tea.
Ravenna, on the other hand, is intriguing and lovely. I love both the "raven" part and the fact it's the name of a city. It sounds like the name of a mysterious widow who is rumoured to have murdered her husband, in the best way possible.