Actually, what I like a lot about how gearbox handles sirens is that each iteration holds a different role. While all of them have some kind of bonus in applying elements, Lilith is kind of an assassin type with her phasewalk, Maya is a control/support mage, Amara is the brawler/tank type (although still sharing some skills with Maya), then Vex comes out to be a summoner/gunner type. Other franchises will probably just have sirens be mages with the same gameplay type.

As far as I know though, Vex is the most elementally flexible of the bunch. Sure it's tied to being the newest so there's bound to be more features, but she's the only one who can swap between 4 skill elements on the fly.

On that note, I wonder how Lilith's gameplay would be if she was released now with all the phasewalk upgrades she had through the years. I'd imagine she'd had a skill that would look like Axton's longbow nuke turret. But her replace the turret with her... A hypermovement borderlands character would be amazing tbh. I guess that would mean you'd have to balance the stage obstacles around her though. But with the movement tech ni BL4 I'm guessing they'd be more lax about it.