Right now Surfer decks have to rely on Juggernaut and Cosmo to beat most of the meta decks (Nimrod, Destroy, Galactus, Thanos + Lockjaw, and Shuri) because the power output of Surfer is too little.
Kang giving us information helps us counter those decks, but only when we have priority! Priority = Good, and therefore Sera = Bad
Sentinel and Lizard = More priority vs. Iceman and Scorpion, and better plays for turn 5. They also don't tie in power vs. Shuri, which is important.
Only play Kang in matchups where you need the information (checking for Galactus or Shuri's Taskmaster/Arnim Zola) or you aren't confident about winning turn 6. If you don't have a reason to play him, then don't--it will make the opponent retreat or change their play and throw you off. You can also use Kang to check for Leech when going against Thanos + Lockjaw decks.
Kang isn't a necessity--he can be swapped for Iceman or Scorpion. I recommend Scorpion.
Another Surfer list which requires Bast and should still work: https://snap.fan/decks/214877/