No, that'd be Fenrir without a doubt. Fafnir is really shitty since you need at least 2-stars she before it becomes better than event Eidolons, but preferably 3-stars.
iirc, the only event eido that can compare to Fafnir is Tiamat (both for water/fire), so would you mind tell me, what event eido is better than 1 star Fafnir?