Spyro 1, 2, and 3 as well as Enter the Dragonfly. Funny enough, when you 100% Enter the Dragonfly, loading your file will just take you to the final boss.
Ratchet & Clank 1, 2, 3, Deadlocked, Tools of Destruction, Crack in Time, Into the Nexus. Probably one of my favorite series when it comes to completing. Not overly frustrating and enough post-game content to make two or three extra playthroughs necessary but stay fun. I couldn’t complete All 4 One because of Online Trophies and I didn’t really bother with Full Frontal Assault.
Jak & Daxter. Excellent game. Your reward for completing it 100% was not excellent.
Sonic Adventure DX Director’s Cut. Even though Metal Sonic is just a skin for Sonic, I’d still say it was worth it. I tried to do the same with SA2, but those letter rankings would just boil my blood and I gave up.
Sonic Riders. Super Sonic is a neat extra, but not worth the trouble it takes to get him.
Sonic Unleashed. Your only reward is achievements/trophies, but I enjoyed this game enough that I did it anyway.
Sonic 06. Again, your only reward is achievements (or nothing if you play on PS3). Absolutely not worth it.
Sonic Generations. Everything I said about Ratchet and Clank could basically be applied here. Just excellent and so fun you want to keep playing after you beat it.
Sonic Colors. I don’t even remember what you get for completing this one but I remember the game being fun overall.
Batman Arkham Asylum. When I say 100%, I mean everything in the story. I didn’t really care much for the challenge maps but I enjoyed figuring out where the Riddler trophies were.
Final Fantasy XV. Absolutely worth it just for the crazy insane bosses you get to fight.
Spider-Man (201

. Honestly this game was pretty boring. I only completed it because of how easy it was.
That’s all I can really think of right now. I’m sure there’s more as I’ve played so many games over the years, but you can’t remember all of them.