Creed has the stats.
He's stronger.
He's more durable.
He's has a better damage soak with or without adamantium.
He's healing factor is way better. Slade's doesn't even register for comparison in comparison to Sabretooth.
Speed/agility is debatable but I'll go with Slade just to give him something as he seems the more agile of the two anyhow.
Slade is a hair more skilled and his tactical combat advantage on Creed also thanks to his enhanced mind.
As Slade puts up a hell of a match but eventually falls down before Creed IMO.
Creed 7-8/10