Hiiiii! What do you like more, Danzo x Itachi or Kisame x itachi?
Both have their own "purpose" and comparing them is basically apples and oranges.
Danzo x Itachi is awful and abusive and feeds my love for fiction that makes me care about the protagonist because of the absolutely depressing, disgusting hell they're put through, kinda like I enjoy Law & Order: SVU, not because I love when people get assaulted, but because the subject matter is very emotional and hard to stomach and makes you super mad at the perp and super invested in the victim. I'm already emotionally invested in Itachi due to his canon tragedy, and DanzoIta amplifies that by a million. Even when I depict Danzo as nurturing or Itachi as willing, it's based on Itachi's canon grooming and isolation.
In a way, Danzo did love-bomb him (in the novels). By real world standards, Itachi would probably be MORE drawn towards Daddy Danzo. His dad is an asshole, is clan are assholes to him specifically, his school and Anbu mates bully him, and his few friends mean so much to him he'd rather not involve them in his troubles - but then, there's Danzo, a powerful man close to the top Itachi wants to reach, controlling conversation for maximum agreement, telling Itachi how special and smart he is, getting him promotions left and right, sharing his worldview (kinda), and most importantly: broadcasting that Itachi is WANTED in his world.
DanzoIta isn't "deliciously horrifying" because of what Danzo does, but because Itachi's situation drives him into such a terrible man's arms. It makes me physically cringe.
KisaIta is the opposite, because even when I depict them in abusive/toxic situations, my bottom line on the ship is that Kisame is a supportive and caring partner who may take things too far and get carried away (like sharks in a feeding frenzy), but ultimately, Itachi is in good-ish hands with him. Yes, by real world standards, KisaIta is still terrible, but within the canon context, i's KINDA wholesome. Even if Itachi was paired with him as a kid and even if he had no choice but smile and obey under penalty of death in his Akatsuki life sentence, Kisame cared about him. If moon dust could have cured Itachi, Kisame would have plucked the moon from the sky and pulverized it to make pills, and if I had Kishimoto on speed dial, he'd probably confirm that XD