I looked at it more closely since the top six keep fees but via.btc does give back some of them at the monment.
So the top five are a no go zero money sense to mine on them.
Viabtc is more complex. they are paying more then the block but not all the fees to the miners.
but the top five simply can not be used.
I'm not pushing viabtc, but that is only their pps+ that pays partial fees. The pplns pays fees and they actually use a 5nd method like kano.is
The do however charge a 2% fee like slush which is more than double the normal kano.is rate.