As Terran
Make:
Raven
Viking
Siege TankDisable or out-position tanks before committing ground units.
Open in the counter tool with Siege Tank tagged ->As Protoss
Make:
Immortal
Tempest
DisruptorRange or burst beats tank lines better than frontal gateway floods.
Open in the counter tool with Siege Tank tagged ->As Zerg
Make:
Viper
Ravager
Brood LordAbduct and Bile make tank positions expensive to hold.
Open in the counter tool with Siege Tank tagged ->
Marine
Marauder
Reaper
Hellion
Hellbat
Widow Mine
Cyclone
Thor
Medivac