1 Attack On Titan: Junior High
This is a parody spin-off of the well-known "Attack on Titan" series. Airing in 2015, it reimagines the original characters as middle school students in a comedy setting. While it maintains some elements from the main series, its tone is predominantly lighthearted and comedic.
2 A Certain Scientific Railgun
3 Koro Sensei Quest
4 Soul Eater Not
It just sucks
5 Magi: Adventure of Sinbad
6 Rock Lee & His Ninja Pals
7 Dragon Ball Z: The History of Trunks
8 Full Metal Panic? Fumoffu
9 Pokemon Origins
10 Magical Girl Lyrical Nanoha
Magical Girl Lyrical Nanoha is a Japanese anime television series directed by Akiyuki Shinbo, with screenplay written by Masaki Tsuzuki, and produced by Seven Arcs. It was spun-off from Triangle Heart so it technically counts.
The Contenders
11 Love Live! Sunshine!!
Love Live! Sunshine!! is a Japanese multimedia project co-developed by ASCII Media Works' Dengeki G's Magazine, music label Lantis, and animation studio Sunrise. It's not a spin-off, it's a sequel.
12 ViViD Strike!
13 Sword Art Online Alternative: Gun Gale Online
I know this is a relatively new entry into the Sword Art Online franchise, but let me tell you, I'd say Alternative: Gun Gale Online was a pleasant take on the GGO side of the SAO timeline. LLENN was such a compelling protagonist and I legitimately found myself laughing almost more than half the time with all the clever comedy coming out of this spin-off. Now THIS is how you do a spin-off RIGHT while simultaneously making it different from the original source material and faithful to it as well. Heh, screw Soul Eater Not!. If it's a cute but awesome anime spin-off other than Fate/kaleid liner Prisma Illya, THIS is what you're looking for.
14 Magical Girl Lyrical Nanoha ViVid
15 Gundam Build Fighters
16 Gundam Build Fighters Try
17 Fate/kaleid liner Prisma Illya
18 The Disappearance of Nagato Yuki-chan