HAHA LOL. Maybe it's best you don't know they English translations to their songs. For example, Chuchu Lovely Munimuni Muramura is my favorite song of theirs and despite it's upbeat chorus it's a horrible song about raping their slaves to relieve stress using tape, rope, knives, vinyl, polyster etc.
It's so wrong but so fun to sing the bridge in a happy voice:
"Daigakusei mou ii na, koukousei mou ii na, chuugakusei mou ii kedo ne <3" (College students are good, high school students are good, middle school students are good, but, you know...<3)
Wow I'm messed up.
What's Up People is an incredible song to karaoke to in a room full of drunk friends, imo.
So I say their latest album Bu-ikikaesu is the best but you probably have it already considering four of the songs you listed are contained in that album. They only have four albums though so just get em all if you like em