I don't know if I would judge whether FFXIV has the worst looking summons out of all FF games judging purely based on Egis, since free companies will be able to summon Primals.
Personally, I would rate FFXIII's summons really, really low. I wasn't a fan of the Transformer summons.
Transformer summons? That's a very good description, actually!
Final Fantasy XIII summons were cool in their own right, but they didn't have the same epic feel to them that, say, summoning Bahamut in one of his many iterations in the series had. Primals, at least, have potential to be truly epic when summoned. Whether they will now or down the road or not, I do not know, but the potential is there. I look forward to seeing what SE has in store for us.
Primary World: Hyperion
Free Company: Jormungandr
Main Character: Fialas Dawnren: Level 60 BRD/AST/MNK/DoL, Level 16-50 On Everything Else