[BreakABone]

Well let's try it by match-up

Price
GCN-$150 with a free game
Ps2- $200

So in essesence, you can get a GCN with 2 games for the same price as a PS2.
But then you factor in memory cards, extra controllers and all those other accessories and they may run you about the same price, but for an initial buy, the GCN is cheaper.

[b]Winner: GCN[/i]

Controller
Well, I'm probably one of the few people in the world who dislike the PS2's controller, I may it works and whatnot, but I have never liked the analog sticks on it for some reason, while the GCN controller takes some getting use to, and even when it does the D-Pad sucks.
But from the time I've had with both controllers, I think they work greatly with the games designed around them.
Winner: Tie

Hardware
I can't really say from personal experience that either hardware is superior as I've never had a problem with either system, but my friends have. Some of their Ps2's stop reading blue back disc and others no games at all. Some folks have had problems with their Cube, but I believe that was more or less dealing with the game disc itsellf, I may be wrong.
Winner: Cube

memory Cards
I have never had any major problems, but for anyone who buys sports game and what not, I can see that the GCN small memory card sucks.
Winner: Ps2

Games
Well this is a weird one. For overall quantity, the Ps2 has the GCN beat in bulks, quality is a subjective matter so I won't touch on that.

Ps2 has in your words: Grand Theft Auto 3, Grand Theft Auto: Vince City (which you can also get on your PC but eh), Tenchu, and a crapload of RPG

The GCN has Metroid, Zelda and well that's basically it.

The FirePro game in development is um, taking it time it seems. And other than Def Jam Vendetta, I think the best wrestling game this generation thus far has been SmackDown: Shut Your Mouth so while I have high hopes for WM XIX (much like I did WM x8 and we all know how that went), I think the PS2 has a large lead in wrestling games since it has a solid base to build upon.

And the RPG thing is really no competition, even though Skies of Arcadia is personally my favorite RPG of all time, you got atleast a dozen high quality ones on the PS2.
Winner: Ps2

What do I recommend you get? Well, I got both so I'm cool, but if I had to pick between the two, I would still go with GCN first.