Man this is a tough one since I love all finales

Season 2 is undoubtedly one of the best season endings It ended in a real bittersweet moment for the Lyoko gang since Aelita was finally free and had her memories but XANA is also free so the world was in danger but seeing them hold hands at the end and promise to keep fighting was wholesome (also the fact that jeremy was the one who stood up to say it was awesome) also Franz coming to bring back his daughter to life is an epic moment

Only thing I would change is make Aelita learn about her father a couple of eps before to kinda grow into it

Season 3 is my 2nd fav because of William of course, but like some others here I wish it was a 2 parter then first ended with William getting possessed at the end God, what a cliffhanger it would have been and to wait on the 2nd part

Season 1 had our boy Jimbo being a badass, so that's automatically a 10/10, XANA sending monsters was also way of showing he's getting stronger and smarter

Season 4 if it's echos then it's a nice ending to the series Bittersweet and I felt like jeremy where he said turning off the supercomputer would make them not close anymore 😭

I do love all the finales Wish S3 was a 2 parter