Is Lightsong a mage or paladin? (cool name btw). But yeah I agree soulbindings are interesting from a thematic sense. I mean you can look at it as like an apprenticeship for your character. There's good rp vibes involved there by choosing who to soulbind with and I'm sure the characters themselves will have personality to them.
But yeah for my alts I'm going by the abilities, originally for instance I was gonna have my DH go Venthyr but The Hunt ability from Night Fae just sounds super fun while Venthyr one sounds boring.
I figure since alt-play will be easier, I will be able to experience all 4 stories on different characters. Only follow 'what would my paladin do' because he is my main.