Damage to tank:
Guristas--------Kinetic / Thermal
Serpentis-------Thermal / Kinetic
Mordu's Legion--Thermal / Kinetic / EM
Blood Raider ---Thermal / EM
Sansha's Nation-EM / Thermal
Angel Cartel----Explosive / Kinetic / Thermal
Mercenary-------ALL
Rogue Drones---ALL
Amarr Navy-----EM / Thermal
Caldari State--- Kinetic / Thermal
Gallente Navy---Thermal / Kinetic
Minmatar Fleet--ALL (varies)
EOM-----------Kinetic, Thermal

Best damage to deal against NPCs
Guristas - Thermal
Serpentis - Kinetic
Mordu's Legion - Thermal / Kinetic
Blood Raider - EM
Sansha's Nation - EM
Angel Cartel - Explosive
Mercenary - Thermal
Rogue Drones - EM
Amarr Navy - Thermal
Caldari State - Kinetic
Gallente Navy - Thermal
Minmatar Fleet (thukkers) - Therm