It seems I answered wrong last lime.
"like" is always jak - after verb or after adjective.
what you wrote would be correct with "jak". It is weird wirh "jako".
"jako" is more "as" . "in position of". so what you wrote means
I love you as (because you are) my brother, I love you as (because I'm your) brother. But it sounds weird.
Ok I think I got it now! "jak" implies a comparison and "jako" an identity?
czerwony jak pomidor : red like a tomato (but it's not a tomato)
kocham cię jak brata : I love you like a brother (but you're not my brother)
kocham cię jako brata : I love you like a brother (and you are my brother)
pracuję jako model : I work as a model (and I am a model)
How does that sound?