In this video I rank 35 of my favourite project sekai songs. This is just my opinion and I will be biased by how fun the chart is, which songs I've heard in the game etc.

Here is a list of all the songs
0:00 Godish
0:10 Daijobu Desu ka?
0:18 Darling Dance
0:27 Ready Steady
0:36 Brain Revolution Girl
0:44 Becoming Potatoes
0:52 Gehenna
1:03 The Intense Voice of Hatsune Miku
1:13 Hatsune Creation Myth
1:21 Heart Forecast
1:34 Marbleblue.
1:46 Imperial Girl
1:54 PianoxFortexScandal
2:07 Don't Fight The Music
2:19 KyuuKurarin
2:32 88 stars
2:43 Aishite Aishite Aishite
2:55 Nonbreath oblige
3:08 Leia Remind
3:21 Miracle Paint
3:34 Bitter Choco Decoration
3:45 IDSmile
3:57 Mr Showtime
4:10 Venom
4:24 Ego Rock
4:36 TondemoWonderz
4:56 What's up Pop!
5:14 Tricologe
5:29 Six Trillion Years and Overnight Story
5:45 Marshall Maximizer
6:00 Shoujo rei
6:25 Phony
6:48 Bug
7:10 Milk crown on Sonechka
7:30 Nijiro Stories

Credit:
Godish PinocchioP
Daijobu Desu ka cosMo@BousouP
Kairiki Bear Kairiki Bear (covered by MORE MORE JUMP!)
Ready Steady Giga (covered by Vivid BAD SQUAD)
Brain Revolution Girl MARETU
Becoming Potatoes Neru (commissioned for Wonderlands x Showtime)
Gehenna wotaku (covered by Nightcord at 25:00)
The Intense Voice of Hatsune Miku cosMo@BousouP
Hatsune Creation Myth cosMo@BousouP
Heart Forecast Eve (covered by MORE MORE JUMP!)
Marbleblue. MisoilePunch
Imperial Girl R Sound Design (covered by Vivid BAD SQUAD)
PianoxFortexScandal OSTER project
Don't Fight The Music Chroma
KyuuKurarin iyowa
88 stars commissioned song by marasy and kemu
Aishite Aishite Aishite Kikuo (covered by Nightcord at 25:00)
Nonbreath oblige PinocchioP (covered by Nightcord at 25:00)
Leia Remind Yuyoyuppe
Miracle Paint OSTER Project (covered by Wonderlands x Showtime)
Bitter Choco Decoration syudou (covered by Nightcord at 25:00)
IDSmile toa
Mr Showtime commissioned song by HitoshizukuP and Yama△
Venom Kairiki Bear (covered by Nightcord at 25:00)
Ego Rock Surii (covered by Wonderlands x Showtime)
TondemoWonderz commissioned song by sasakure.UK
What's up Pop! Capchii
Tricologe commissioned song by Niru Kajitsu
Six Trillion Years and Overnight Story kemu (covered by Leo/need)
Marshall Maximizer Hiiragi Magnetite
Shoujo rei MikitoP (covered by MORE MORE JUMP!)
Phony Tsumiki (covered by Nightcord at 25:00)
Bug commissioned song by Kairiki Bear
Milk crown on Sonechka Yuzy (covered by MORE MORE JUMP!)
Nijiro Stories commissioned song by OSTER project

Outro song
Still in my heart Psyqui