Gamecube has more of the games I'm interested in, so that for me. Maybe if if didn't find Naughty Dog games so overrated. Rogue Leader being my favorite game of the 6th generation doesn't hurt either.

How can you forget persona 5 one of the greatest jrpg ever

PS3 by far. Its one of my favourite consoles and library thats frankly ridiculous. Gamecube on the other hand only had a couple of games that really stood out to me, which was Wind Waker and Smash. 

In one generation on PS3, we had; Uncharted 1-3, Mass Effect trilogy, Bioshock, Bayonetta, Demon's Souls, God Of War 3, MGS4, Vanquish, GTA IV and V, Red Dead Redemption, Max Payne 3, Ratchet and Clank: Tools Of Destruction, Journey, Portal 1+2, Yakuza 3 and 4, Catherine and tonnes more.

You'd be right.

OT: I didn't own a GC during it's time or even after it's lifespan, but I did get to play REmake at a friend's place as well as Resi 4 as well as some Mario titles.

I owned a PS3 until it's warranty ran out. PS3's were still expensive back then and I wasn't going to get a "second job" just to go for a second PS3, I just went with Xbox after that.

List of games I owned on PS3 at the time were:

Armored Core 4

Bladestorm: The Hundred Years' War

Asassins Creed

Burnout Paradise

Bayonetta (Jesus christ was this a mistake purchase) 

Army of Two

Bioshock

Armored Core 4: For Answer

C&C Red Alert 3 (Literally the only game I have ever triple dipped on)

MGS4

Resistance

Heavenly Sword

Tales of Symphonia was on the GameCube and is one my favorite rpg's of all time.  Baten Kaitos 1/2 were both fantastic.  I didn't play Fire Emblem, but if it was anything like the Switch one I'm sure it was great.  Even with those the PS3 had a lot more quality rpg's, but the Gamecube had some real gems. 

PS3 by far. The games on that system were amazing, and Sony's 1st game stepped up to new heights.

Gamecube's library was lacking to me. Probably my least played/favorite Nintendo system I owned.

PS3 by far. Vastly superior library.

PS3 by far. Gamecube had Metroid Prime, Smash Melee and, Windwaker and the weakest mainline Mario but besides that not much that interested me.

PS3 had Uncharted, Ratchet and Clank, Littlebigplanet, Killzone, The Last of Us, Ni no Kuni, God of War, Demon Souls, inFamous, I even really enjoyed the less popular titles like Warhawk and Star Hawk. And there were also multi-plats as well like The Elder Scrolls Fallout etc. Despite it's launch i always thought the PS3 was the best of it's gen. better than the 360 just for the games library alone.

PS3 wins for me.

So far ps3 is my favorite playstation console so that should tell you everything.

Ps3 is the weakest seven-generation console( Wii, 360, DS, and PSP are better). But the seventh generation is the better generation. 

Gamecube is the weakest fifth-generation console. And the six is not the better generation.