Slashing Falcon Dragonbound, Sylvie

Despite not needing an active for full multiplier, people are probably going to use Dioses with her anyway :/

If you're using Dios, no. RLB has x81 while Sylvie only has x64, and she is bindable, only one SB, but for long dungeon like Arena, she might surpass RLB because she only needs 6 wood orbs to activate her LS and doesn't need to use skills and with x4 RCV, stalling is a breeze if you need to collect 6 wood orbs between floors.

It really is a great leader skill! Dual 25% damage reduction is equivalent to a 77% HP boost, but unlike a HP boost it doesn't increase the amount of recovery you need to heal. The 64x multiplier (if you use two) is lower than Reincarnated Liu Bei's 81x multiplier, but you only need 6 orbs to activate it, not 10. And with 6 orbs you can make an extra row on a 6x5 board, which potentially means an extra 80% damage from her (dual) row awakenings alone!

RLB teams often fall down in two areas: skill-bind resist and HP. She covers those, although unlike RLB she can be bound. End-game content has gotten so crazy that I'm not sure even she is up to it, but as long as you can cover her with bind recovery (e.g. from RLB himself) she can definitely do any dungeon RLB can and probably others too.

In terms of farming benefits, since she does only need 6 orbs to activate, she can work very well with row makers for a system-like farming team, something A/RLB cannot do, which is another point. Biggest thing separating them in farming is mainly just Damage Reduction vs Bindability. One might be more useful than the other in certain dungeons.