I originally started watching anime before going into manga. but thanks to me being stubborn I ignored a lot of really good animes back then 🙁

So, I am looking for must see animes, either a classic or just something you like today. I don't mind if they are long, actually I prefer if they are long, just not as long as one piece (I love 😀 the series but I don't think I could watch another anime series with 500+ eps).
-I prefer no romance but if there is some I don't mind
-love supernatural/ sci-fi/ fantasy/ adventure

"They were traps? I thought they were attractions"
Killua (Hunter X Hunter)

Few titles on the top of my head
Monster
Berserk
Mushishi
FMA Brotherhood

I know you do not prefer romance but you asked MUST SEE:

Sword Art Online (Sci-Fic/Fantasy/Adventure/Romancd) The best anime of this season. Really reccomended. Light novel adaption.

Steins;Gate (Sci-Fic/Romance) One of the highest selling & critically acclaimed anime.

Spice & Wolf (Romance/Fantasy) Its a light novel adaption.

Kiba (Action/Adventure/Fantasy)

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Mahou Shoujo Lyrical Nanoha 3 season series. (2nd season is the best!)
Sci-Fi not fantasy or supernatural. (Which you will realize later on if you watch it)

Seconding SAO, Steins Gate, Spice and Wolf, and Kiba

Edit:
Want a sci-fi comedy? Baka to Test is your oxygen de-supplier.

Is this me in a nutshell?
Pretty much.
[img]http://www.dragonflycave.com/wpay/ninetales.gif[/img]

FLCL
TTGL
GTO

thank you, I'd definitely rather watch a "must see" anime than miss out on it just because it has romance

"They were traps? I thought they were attractions"
Killua (Hunter X Hunter)

MUST SEE!!!!

• Code Geass
• Code Geass R2

ꉂꉂ(ᵔᗜᵔ*)笑

Anohana: The Flower We Saw That Day is fantastic. Maybe not your thing. I also suggest Break Blade

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• Cowboy Bebop
• Ghost in the Shell
• Planetes
• Welcome to the NHK!
• Monster
• Kino's Journey
• Mushishi
• Baccano
• FMA Brotherhood
• Spice and Wolf

Something different:

• Tales of Street Corner

These are series I like that I think every anime fan needs to have an awareness of:

Revolutionary Girl Utena
Princess Tutu
Gurren Lagann
Tiger & Bunny
Loveless
Ouran High School Host Club
Gintama - long, you don't need to watch all of it, but I would recommend at least sampling it.

None of these are what I would call romance, except for the tacked-on ending of Ouran, and again with the exception of Ouran, all are either fantasy or science fiction.

samurai champloo princess monoke howl's moving castle kaiba and cat soup

My Must Sees, no particular order
*Gundam Seed - Mecha+ Space drama+ huge battles+ political intrigue
*Gundam 00 - All the gundam goodness done in our timeline using near realistic science
*Crest of the Stars (I&II) and Banner of the Stars (I/II/III) - fairly long and amazing space opera series
*Claymore - One of the best Seinen series (no clue how it claims to be shonen. WTF)
*Saiunkoku Monogatari 1&2 - Historical Fantasy that is technically a reverse harem romance (and shoujo) but really not the focus of it. It is far more political and action oriented
*Full Metal Panic! and Full Metal Panic! The Second Raid- Mecha in near future, super brain kids, all around awesome
*Rahxephon - NGE with better animation and minus the Shinji... plus weird parallel dimensions
*X TV - Main character is the world dragon, and will choose good or bad. Also amazing sword fights.
*Air Master - The best choreographed fight anime I have EVER seen. If you skip the moo cow and little girl all the characters are cool.
*12 Kokuki - If you ignore the last few episodes, hands down one of the best fantasy/ another world series out there. Character growth/ development to the extreme, even for a shoujo
*Fushigi Yuugi - You will hate me for it, but this is a must see. It defines the genre. If you get through all of it, you have my praise... and pity to join this dubious club (and yes I am part of it).

Comments on anime already suggested:
Berserk - One of the best fantasy/historical Must See
Monster - Creep to the extreme, pseudo critique on the human condition, mindf* Must See
*Kiba - Meh. It had huge potential but never quiet got there. Maybe if it went more Seinen than Shonen?
Spice and Wolf - Could never get into it so don't have a comment
SAO - Good anime but wouldn't consider it must see. Also not finished
Steins;Gate - Ridiculously overrated... though way better than Chaos;Head, both are sort of mindf series though not as much as they could be. Thus far Robots;Notes shows promise but am a few weeks behind it.
*FMA Brotherhood - Need to sit and watch it. From what I heard it was better than the first and the first could be a contender on this list.
*Code Geass & R2 - One of the best out there. Must See
*FLCL - All the crack of Excel Saga in 6 episodes. Must See
*Great Teacher Onizuka - Really amazing series, though not really in the types you asked about. Must See
Planetes - would put this on the maybe. Interesting, especially realistic with today's concern about waste.
Cowboy Bebop - This is one of the gateway animes. It is very good and one of the few that is almost as good in English Dub. Must See
TTGL - I can not stand this anime. F the Heavens, my mech is big enough at 50 ft tall.

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Be the Ultimate Ninja! Play Billy Vs. SNAKEMAN today!

although i don't watch much fantasy/adventure/sci fi anime, these should fit. i think these are a must see for any anime fans.

Kara no Kyoukai: The Garden of Sinners
7 movie series of action and fantasy with a hint of romance. animation is top notch. one of the few good things that have aired recently. highly recommended for anyone.

Fate/Zero
really depends on tastes. i loved it, but i'm a fan of the Fate series. again, one of the few good things that have aired recently.

Mahou Shoujo Madoka Magica
a show that had most of the anime community talking about it. people try to justify that it's revolutionary. i don't believe it is; but i do think it's a pretty shocking anime that gets addicting near the end.

Death Note
pretty popular. it's a good watch that gets addicting. however, there's no rewatch value after you've seen how things progress the first time.

Slayers (particularly Slayers Next)
a classic fantasy adventure series. it's a pretty fun show, but it is long. simply a classic for its genre.

i disagree about Sword Art Online being a must see. it's a fun watch, but the story is weak with plot holes. it starts off strong but then goes downhill. however, it is entertaining if you don't take it seriously.

some of ur posts silvermoon and sndric in particular makes me pissed off lol

gundam seed and gundam 00 = sex and should be avoided like the plague if you are att all interested in gundam
and silvermoon wtf
do you only watch uber pretentious garbage?
and when im on it CLAMP ddesigns are horrible

so...
gundam x
dark and diffrent gundam...overlooked gundam show

macross 7
only problem with this is that the main character/main singer of the show just cant sing
his voice is horrible

detroit metal city
manages to be just as funny and sometime even more funny than the manga

grappler baki
awesome violence anime
and alot more pleasing to the eye than the manga

Moeyo Ken ova and tv
awesome
supernatrual/fantasy thing comedy

JoJos bizarre adventure OVA [you could try the new tv show too...not too bad]
diffrent than the manga but awesome on its own

Denpa Teki na Kanojo ova
gold

Angel Beats
Summer wars (movie)
the girl who leapt through time (2006) (movie)
Cardcaptor Sakura
X Slam Dunk

Support:
Code Geass
Fullmetal Alchemist
Gundam Seed

For Ouran Hight School Host Club, I agree that its quite entertaining, but I don't think its a must watch anime.

About whether SAO is a must see anime or not, I'll add some spice to the disagreement: read the light novel. The anime isn't as good as the light novel.