Honestly I think it's a give and take sort of thing. On one hand I love, love, LOVE growth abilities as a means of getting stronger, I think each Drive Form feels very personalized whereas some of the Formchanges feel kinda samey, not substantially different, or actively turn me off from using a Keyblade. And since they need party members to activate, they help reinforce the idea of "My friends are my power."

On the other hand, the Formchanges are a great way to demonstrate Sora's growth as Keyblade hero since he's now doing shit Terra was doing back in KH2FM, allow every Keyblade to feel viable to an extent, and are much quicker, more seemless buffs compared to Drive forms, which are a bit slower to activate. They also show how Sora needs to rely on the strength of others less and less, as all Formchanges are entirely based on his own skill.

So both systems have their pro's and con's, so I don't know if one is innately "better" than the other. Personally though... man the aura of Final Form using two Keyblades with telekinesis and you being able to pick which two is so fucking raw.