Nintendo
I've played several Castlevania games, didn't really get into them; in fact, generally beat them once and then had no desire to play again, or lost interest before I beat them once.
I've played Suikoden 2, thought it was a pretty average jRPG--above average plot, but overly simple combat system.
I haven't played MGS yet; it's on my to-do list.
By comparison, Nintendo's got Fire Emblem, Advance Wars, Paper Mario, and...yeah, pretty much Intelligent Systems beats Suikoden at their own game, (Fire Emblem > Suikoden is fairly obvious to me). I'm not as into Metroid as I used to be, but I'll still take it over Castlevania; actually, I'd take Super Paper Mario over any Castlevania I've played too, so R&D1/Intelligent Systems beats Konami at Metroidvanias.
Admitedly, outside of R&D1 and Intelligent Systems, Nintendo isn't that great, but fortunately for them the non-EAD games are good enough here.
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Cats land on their feet. Toast lands peanut butter side down. A cat with toast strapped to its back will hover above the ground in a state of quantum indecision