Skimmed the thread and I want to know what's up with all the Solomon hate? Book of Raziel is usable every 3 turns and gives an attack boost when used as Solomon, plus she gets higher base ability damage which helps clear out some fodder when using an EX skill that hits all enemies. Solomon's Ring individual hits can raise or lower the gauge for the enemy to kick them out of Raging which saves your team health and causes the enemy to take more damage when they're in stun status so a sort of hidden damage buff for your party since your entire team gets to use their basic attacks which can be buffed which with somebody like Beelzebub sending your party into the Rage state can be pretty significant. On the other side you can use her abilities to break stun sending them into the Rage state before your turn which will end your half of the turn with them going into the Stunned state instead of getting a turn with the Rage state and if you pass Black Propaganda and have Satan you can pretty well keep them from using their most powerful abilities. I agree that Mordred is probably the strongest contributor in terms of damage for raids, but there are other things and with the events by yourself ranging the enemy guages using Solomon isn't a bad tactic plus Solomon is cheaper and her master gives ability damage which is pretty much always useful. You also have to consider weapon specialties Solomon can use staves and having a SSR burst is worth something if that's your only option and depending on your weapons that 20% bonus can add up. To my knowledge the damage added from the DoTs doesn't increase your per turn PP for raids so whilst you are dealing more damage effectively it's not going to help you get MVP since it goes by PP not Damage.

Solomon's ring actually does end up doing solid additive damage should their only be one target that gets hit by every tick and in terms of completing levels each hit is separate so there's very little waste when killing mobs which that damage could potentially add up depending on what type of luck assembling a team you've had.

I'd take Solomon over D'art, Siegfried, and Arthur personally and Solomon is cheap on SP. Andromeda is only really useful if you need that healer if you don't she's lack luster and if you just need a little healing IMO Joan is better for that.

IMO
Mordred for Raids

Andromeda if you need a healer

Joan for general purpose

Solomon and Arthur are both acceptable and IMO they're pretty equal.

Siegfried and D'art are the worthless ones IMO.