What are your opinion on Bat Swarm vs Meteor and their morphs :P
Batswarm if you have access to them, meteor if they are on the wall or below on the ground.
Batswarm will ALWAYS be superior to all ultimates because you can move it around with you and people can't escape the damage. If they try to dodge roll away you just follow them.
The visual is VERY subtle making it hard to detect until to late especially in big battles. There is also the survivability BS gives you.