Already seen Gintama both Anime and Manga... It really is one of Masterpiece in my opinion
Gankutsuou is The Count of Monte Christo, but in space, and it's art style is like, weirdly smooth asf, like, they have these like static fabric like colors that when characters move, don't move, it's kind of crazy but rad. (the design choice I mean)
Welcome to the NHK is pretty transformative if you watch it during a certain part of your life (early 20's I'd say, maybe upper teens)
Monster has arguably the best villain in anime (bye bye Light Yagami, bye bye Griffith)
Overall all of those anime are at least decent, some of those series are truly exceptional. Can't go over all of them. Pretty much all of those anime were at least one of the coolest anime to come out during it's release season, and some of those are genuine top tier anime.