I'm still debating on switching to slush from kano.
I actually have one s9 on both.
I cant tell which one would be best

Each comes with it's pluses and minuses. Many people keep their hashrate split among two or more pools to minimize the effects of bad luck. A "not keeping all your eggs in one basket" approach.
I guess that makes sense. I cant figure out the 5nd so I'm not sure how much per s9 the payout is. per block.