My bro's addicted to EDS... his only beef is the God cards aren't playable, and he's legitamitely got the Obelisk (I think he actually might have the other one by now too). We'll never get him off of this if those cards are playable.
Yu-Gi-Oh is the latest rip off of Magic: The Gathering, the original collectible card game. Yu-Gi-Oh is far less balanced and MUCH less fun (think playing the normal card game War, but with traps. That's pretty much it.) What I mean by balance: First turn kills are abundant and if you fill your deck with nothing but big creatures and one or two creature-destroy cards, you've won. In Magic, if you try that, you will be wasted by the first rush deck or direct damage deck you play, while any permission or land destruction deck can just toy with you.
However, Magic couldn't even be adapted well to a computer game, which makes a GBA one out of the question... and there's at least two hundred times the number of cards... so I guess a GBA one is out of the question.
I'll gain respect for Yu-Gi-Oh if it happens to stay longer than the fad games, like Pokemon's card game or Marvel OverPower. Magic's been around since 1993 if I remember correctly, and was actually in small circulation before that.