Which siege weapon in ESO PVP does the most damage?

Which siege weapon does the most damage, to players and to buildings?

2 Answers

I experimented with the siege engines on resource towers and on the dummies on the training field, and got some numbers about them:

Balista
2000 to structures
270 to Units
Fire Balista
1000 to Structures
1080 to Units over 3 seconds (360 per second)
Lightning Balista
1000 to Structures
810 to Units over 3 seconds (270 per second) and stun

Scattershot Catapult
2000 to Structures
180 to Units
Meatbag Catapult
500 to Structures
540 to Units over 3 seconds (180 per second)
Oil Catapult
500 to Structures
451 to Units and ensnare

Stone Trebutchet
2500 to Structures
360 to Units
Iceball Trebutchet
500 to Structures
225 to Units and ensnare
Firepot Trebutchet
2000 to Structure
higher than 2400 to Units. The first dot destroys a 800 hp dummy, so I couldn't really measure it

Battering Ram
It is difficult to measure it, because it may vary between having 3 to 6 players near a ram, and you need an actual enemy keep door to measure it, and it is a mess during battle.

I didn't have the opportunity to test the siege weapons against other siege weapons in the field.

I think this is also explained during the campaign introduction/tutorial, but basically you've got five types of siege engines/deployables:

Ballistas offer the highest single target/small area damage and are most effective against single players and other siege engines.
Catapults offer the highest area of effect damage as well as extra effects such as snares (also available on other siege engines, but less effective due to smaller area).
Trebuchets offer the highest damage against structures such as walls, gateways, etc.
Rams may only be used against keep doors for obvious reasons.
While technically not siege engines, forward camps are purchased and placed just like siege engines and allow a limited number of players to use them as wayshrines when respawning.