Out of this group, Sonata. Though Derpy’s a close second. Sonata’s the only one of the Sirens who seems redeemable. She’d probably respond well to kindness once she got used to it.
No, but for real I’d say Sweetie Belle. Really sweet personality, and she manages to be fairly without being obnoxiously so. Kudos on the writers for that. Plus she’s basically me as a kid: scared of anything with the slightest risk, not too quick on the uptake, and rarely thinking through things but still having the he’s intentions at heart. How can I say no to that?