I guess I’ll chime in. I bought a new Xbox 360 last summer when my launch model broke, and I’ll replace it again if this one does. I think the PS3 has a better library of exclusives but if/when it breaks, I probably won’t buy another one.
The Xbox 360 has backwards compatibility with the original Xbox, which is a huge draw for me (especially since my fat OG Xbox’s disc drive is on the fritz.) Ninja Gaiden Black, Panzer Dragoon Orta, Fatal Frame, Jet Set Radio Future and Breakdown are all some of my favourite games and I’d hate to lose access to them. Sega in particular leaned hard into the original Xbox, and if you look at its library (the aforementioned plus Shenmue II, Crazy Taxi 3, Outrun 2, and oddballs like Gunvalkyrie) it’s pretty clear that Sega channeled their umbrage toward the PS2 into Microsoft’s system up until about 2004. You’ll need a HDD to play any of those, and 4GB is pretty anemic. It uses a 2.5mm laptop drive but you might want to do some research on which models it’ll take; you might even be able to use an SSD, I’m still using my absolutely ancient 20GB drive. I think USB drives are supported too.
As far as the 360’s exclusives, there’s three niches where it really shines. I’m going to dump the obvious Gears of War/Halo games in the dirt because, honestly, who cares anymore. Then there’s the first-party Microsoft games: Fable 2, Viva Pinata and (my favourite) Crackdown. Once again, weirdly, some great efforts were submitted by Japanese developers. There’s a fistful of traditional JRPGs (Infinite Undiscovery, Blue Dragon, and Lost Odyssey in particular) if that’s your thing. And then there’s the entire reason I own an Xbox 360: the things got dozens of shmups. I think that the 360 was the basis for that generation of arcade games in Japan, so it made sense for Cave to also release home versions of the games they were developing for the hardware anyway. It’s got the best shmup library since the Saturn, although the Switch might be rivaling it now. I wouldn’t discount the Xbox Live Arcade either, there’s some exceedingly scarce releases like Guardian Heroes and Radiant Silvergun kicking around on there.
PS3’s got some back catalog to flex as well. All of the Metal Gear Solids, most of the Resident Evils, God of Wars, Jak & Daxters and Ratchet & Clanks, as well as the excellent Sly Cooper games, Ico + Shadow of the Colossus. I really can’t comment on The Last of Us Some people are into the Infamous, Uncharted and Resistance series; I’m fairly lukewarm towards them all. I’ll take Prototype for my open-world superpower dickery and console shooter controls are emphatically not my forte. Curveball titles would be Siren: Blood Curse (or whatever its US title was), 3D Dot Game Heroes, Tokyo Jungle, Folklore, Little Big Planet, and the utterly superb Wipeout HD.
I bought the thing to play Demon’s Souls and that’s still my pitch. I know everybody’s formed their opinions on the *Souls games by this point, whether it’s joining the cult, bouncing right off or getting preemptively scared away by the inundated, and I’m probably not going to change anyone’s mind here. Demon’s Souls was my first experience with it though, and it remains (in my mind) darker, more esoteric, foreboding and atmospheric than any of the Dark Souls games (I don’t have a PS4, but when I do it’ll be for Bloodborne and Bloodborne alone.) The locations and enemy designs are some of the best in all of gaming, and I’d be untrue if I didn’t wholeheartedly recommend it to anyone, with the caveat that only a certain strain will enjoy it. I still think it should be experienced.
It sounds a bit like you’re mostly in it for the multi-plats though, and. They’ll almost unanimously run better on 360, Red Dead Redemption included. I’ll throw in Armored Core 4/5 and Nier as possibly interesting games for that category.
In short: PS3 if something catches your eye, 360 for the middle of the venn diagram (and shmups! Glorious, beautiful, top-down blastin’ zappin’ blazin’ rootin’ tootin’ shmups!)