Sorcerers struggle with variability/adaptability, at low levels they don't have enough spells known to really cover their bases and adapt to situations.
Their point of struggle is that because they can't choose the best spell for that particular situation, their spells are less impactful than a wizards, the spell is still useful but not ideal. They make up for it by spamming the less efficient spell enough times to make up the difference.
A way to capitalize on the sorcerers strengths and uniqueness would be multi spell synergy. The ability to combine a multitude of spells together in order to create a special effect, this is something wizards can't afford to do because every single spell they cast needs to count for as much as it can. They can't afford to combine too many things together in order to get a desired result.
Lumomancer and Shadow adept accomplished this back in v4 (especially Lumomancer), what was most fun about the class wasn't how broken the two spells that broke the kit was, but rather how much synergy its spells had with each-other, made the class feel different.
As for suggestions for kits?
I suggest we look into giving each sorcerer bloodline a power that functions similar to Fallow Staves, an infinitely spammable item with a minor effect that scales a little bit with caster level, who's effect varies based on what you're using it on (use on self to get a buff with a cooldown, use on floor to get an aoe effect, use on person to have a targeted effect, use on door or object to have a utility effect)
This capitalizes on what sorcerers are all about, weak but adaptable effect that makes up the difference in potency with quantity or with the fact that you can combo multiple things together in order to get a better result.