I agree. The angel had a far more loving relationship with The main. Firika stayed at the side-lines, got pissed when she wasn’t getting the action and slapped Sera after she Yamato not to risk his life for hers and even healed him. First episode showed them casually walking without much hassle, Firika just popped up, teleported him into the sky and had sex with him out of the blue. I don’t like Firika at all, just seems to insecure in the same vein as characters like Naru from Love Hina or Sohara from Heaven’s Lost Property. So in short, I think Sera is best girl.