Omega Ruby has the version exclusives that most please me. I prefer Groudon to Kyogre, Reshiram to Zekrom, Ho-oh to Lucia etc. I would argue that Groudon is not only better as a Pokemon, mainly because Desolate Land helps him more than Primordial Sea helps Kyogre, but that he is a more imposing threat story-wise.
Kyogre is phenomenal, but the thought of being slowly burnt alive is even more terrifying to me than drowning at sea. I also think Groudon is a more unique creation, we have many great variations on sea monsters, and Kyogre is one of my favorite designs yet I don't think we've seen anything quite like Groudon.
It also helps that I am a big fan of the 6th Pokemon movie: Jirachi Wishmaker, and like the way they depicted Groudon and illusions of him in that film, so capturing Groudon in RSE and Oras always meant more to me.