I recently acquired a GameSir X2 Pro (it's still on its way), and I downloaded some games that I've always wanted to play and/or looked interesting.
Among the ones I'm most looking forward to playing are God Of War (PSP and PS2), Resident Evil (1 on PSX as I love the franchise but never had the opportunity to play 1 decently) and Code Veronica: X.
Prince of Persia, ICO, DMC3, Genji, DBZ Budokai Tenkaichi 3, Onimusha etc. Almost all of PS2's popular library is in my phone's memory.
I'm also looking for a recommendation, but this time I'm looking more around the PSP or maybe GameCube/Wii. I tried to emulate the Vita on my Poco X3 Pro, but with little success it was more than worth the effort.
So happy to read this, I just bought mine and it's due in a week or two. I was previously using a clip with my DualShock 4, but the weight distribution left me with a weird feeling.