Just looking at the two as players and not factoring in off-the-field issues, I think I would go with Kirkpatrick over Janoris.
This league's receivers are getting taller, faster, quicker, stronger, et cetera, not smaller.
We've currently got a roster full of 5'10" corners and I don't think it's dieing for another one. Kirkpatrick gives this secondary some much needed size for matchups and certain situations.
As someone else stated earlier, the combine will reveal much about Kirkpatrick's speed. I think the kid has great fluid hips and I love the fact he's a willing and capable tackler. I do wanna see what his straightline speed is though.