taking you literally and i'm going to go by decade here. only 2 per decade, which is gonna kill me for some of the later ones, but otherwise i'd be here all day

1970s

• mobile suit gundam: the 1979 anime that started it all, this is the best place to start for one of the biggest franchises in anime. fascinating to see where basically every scifi trope in anime comes from. but it's also just an incredibly well told war story on its own, no broader context necessary. the way the mystery of char expands and gets revealed is incredible, amuro's trauma is explored in some interesting depths, the whole cast is really strong. and it's got classic scifi psychedelia in ways that make it obvious that it was coming off the tail end of 60s counterculture but in a really unique way that manages to feel super profound
• rose of versailles: oscar dejarjayes is the (fictional) captain of the royal guard in late 18th century france, serving under marie antoinette. a woman raised as a man so she could be her father's heir, she's basically the best at everything but is kinda dumb. courtly drama! exploration of gender in some kinda problematic but still very interesting ways that are very progressive for the 70s! and then the back half depicts france just falling apart in the leadup to the french revolution as the nobility completely fail the people. unrest builds, things get worse, and the french revolution happens

1980s

• armored trooper votoms: in the grim dark future of the whatever millennium this takes place in there is only war. chirico cuvie is an ex-soldier who just wants to figure out why his unit betrayed him, and is forced to live through the plot of every single action movie made in the 80s. he suffers through a cyberpunk megacity full of corrupt cops, underground mech fight rings, mad max style biker gangs, multiple prison breaks, and an evil priest. and that's only in the first arc! later he fights in the vietnam war, gets trapped on an abandoned spaceship where all his sins are laid bare in front of him, wander the wastelands of a desert planet while being chased by someone after revenge, and ultimately collapse a massive galaxy spanning conspiracy. fantastic stuff, and the mechs in it are some of the coolest of all time. make sure you watch the sequel ovas because they rule.
• dallos: what if the battle of algiers happened in space? on the moon? and had mech fights? and was the first ever ova and was just absolutely gorgeous classic 80s animation? just really good stuff, the generational differences within the colony are fascinating

1990s

• revolutionary girl utena: utena tenjou has a dream. she's going to become a prince on a white horse, just like the one who saved her when she was young. no hyperbole, the greatest show of all time. a surreal exploration of gender roles, funny animal antics, memory, sexuality, and the tyranny of the automobile. but most of all it's about abuse, systems of power, and how to break free. if you watch one show i recommend please make it this one, i cannot say enough good things about it. infinitely gayer than you'd expect from a show that aired in the same timeslot as season 1 of pokemon. content warnings for a LOT of shit, lmk if you need anything specific
• turn a gundam: if you only watch one gundam it should be this one, it's the best that gundam gets. after 2000 years, the people of the moon come down to resettle an alternate earth that's basically pre world war one europe. the closest i think a tv show could come to matching (and honestly sometimes surpassing!) the pastoral kinda steampunk aesthetic pioneered by hayao miyazaki. incredibly gentle and brutally horrifying in equal measure, with all the damage you might imagine caused by asymmetrical mech warfare. also the protag has Gender in a way that's remarkably well handled considering it was 1999. here's a scene from the first episode that gives me goosebumps from how beautiful it is

2000s

• hellsing ultimate: if you like schlocky b-movies you'll love this. hyperviolent in a way nothing else on this list is. vampires led by van helsing's granddaughter and her servant alucard vs catholic supersoldiers vs nazis (most of the nazis are also vampires). imagine the coolest shit you can imagine vampires doing with the biggest guns you've ever seen (like, dual wielding anti-tank rifles is the START) and imagine it's all presented with massive amounts of style. content warning for sexual assault, both threatened and enacted
• death note: kinda edgy incredibly dumb homoerotic mind games, just a lot of deeply ridiculous fun. light and L going back and forth while L's theme plays is peak. nothing comes close. simply the best to ever do it at the things it's trying to do

2010s

• revue starlight: the weirdest audition for a high school theater program i've ever seen. 7 girls are competing for the lead role, but this manifests as them having beautifully animated sword fights under the supervision of a giraffe. each girl gets her time in the spotlight where her own specific past and reasons for wanting the role are explored. all of them get real homoerotic with it. fascinating show with a lot of stuff to say about the nature of art and passion. the movie is even better than the show, so make sure you check that out after
• nichijou: absolutely wild comedy that tries every style in the book, cannot recommend it enough. words can't really describe what makes the high school antics so good, but it's willing to throw everything at the wall and every joke lands. it can have surreal pythonesque humor about strange societies that live on blimps right next to a very grounded comedy bit about 2 girls chatting and fucking with each other and they both work so well. i watched an episode at a time with friends over the course of months in between other stuff as a little treat and loved it

2020s

so i actually haven't watched that much anime i love this decade, but there's been some good ones

• bocchi the rock: kinda comparable to nichijou in some of the humor styles, but this has a much more structured story about an incredibly anxious high school girl joining a band and making friends. very pleasant, with some hysterical ways of portraying her fears and a super strong cast including the VERY attractive alcoholic bassist mentor. also has some incredible scenes when they're performing, making you really believe this high school band has what it takes to maybe make this a full time thing one day. i'm rooting for them, and i'm rooting for bocchi to get a girlfriend! (it's very funny that the series has a few lines that make it clear she's gay but it never comes up on account of the crippling anxiety and resulting lack of any relationships or even crushes)
• keep your hands off eizouken: incredibly creative show about a crew of autistic teenagers who want to make anime. the 3 have to figure out all the different things it takes on their own, without letting their imaginations run wild and outstrip what 2.5 animators can do in a relatively short period of time. just a fantastic show, with one of the most energetic and fun opening credit sequences of all time