These might not be the most niche out there but I think they're worth checking out. For Gamecube titles I'd say the first two Pikmin titles, the original Luigi's Mansion, Mario Party 6 and Super Mario Sunshine. For Sunshine I'd recommend the Sunburn mod too, I feel like it enhances the game quite a bit. You can ask me for that if you're at all interested. For Playstation games I'd recommend the Persona series, the Metal Gear Solid series (MGS 3: Subsistence being one of my favorites.), Parappa The Rapper and the Kingdom Hearts series. Dreamcast games like Jet Set Radio and Guts' Rage are also interesting. Little oddities like Warioware, Tomodachi Life, Rhythm Heaven, Professor Layton and Phoenix Wright are also a great amount of fun. I hope this is helpful and I apologize if it's a little all over the place! Cheers and enjoy!
"Gaunt granite climbs where gulls wheel and glide, mournfully glide o'er my island."
As the title states, I want to hear what everyone's recommendations are! You can get super niche, idc if you're the only person you've known to ever play the game I love obscure gems.