Any spelling is fine. [name_f]Katherine[/name_f] is probably the most classic but go with what you like best.
I like both, always been a fan of the name. [name_f]Kathryn[/name_f] is more unique and has a twist on it. Super cute for a baby and perfect for when she grows up, too. 
I also like [name_f]Catharine[/name_f] and [name_f]Kathrine[/name_f].
Personally [name_f]Kathryn[/name_f] is my least favourite spelling however the name itself is very regal and elegant my favourite variant is [name_f]Catherine[/name_f].
I prefer the [name_f]Catherine[/name_f] version of this name.
Perhaps you should go with [name_f]Catherine[/name_f] then! 
it’s a lovely choice
I love all spellings of the name. I think I personally prefer the [name_f]Katharine[/name_f] spelling, then [name_f]Katherine[/name_f] and [name_f]Kathryn[/name_f]. [name_f]Kathryn[/name_f] (this spelling) is a family name which makes it even more special to me.
It’s elegant but I think it also has personality and charm. There’s such good nickname potential too.
Maybe. I actually prefer the C spellings over the K, but [name_f]Catie[/name_f] or [name_f]Caty[/name_f] does not look right as a nickname. As a middle name, [name_f]Catharine[/name_f] or [name_f]Catherine[/name_f] would work well though.
It’s my name, and my favorite spelling of all of them! I think it gives a completely different vibes from the alternatives - it feels more modern and cool versus classic and elegant. However it’s not most people’s default spelling, so I always have to correct people when they write it.