My favorite is Mysterious Girlfriend X, because it's all 3! It's not out yet, but it's coming out in April and I can't wait! *squeee*

I never would have thought a manga based around drool could be so awesome.

I've never watched a decent anime romance show hah. I mostly read them in mangas because they are much better. But I must say, there is one anime romance show that everyone is missing and missing in the romance anime history which is Ranma 1/2. xD I never get to see good mystery and school life anime.  :/

Case Closed- For those who don't know it's about a teenage detective, Jimmy Kudo, who gets shrunk after being "poisoned" with an experimental drug, he then moves in to live with Rachel, his crush,  and her father, Detective Richard Moore, a washed up detective who was put out of work thanks, to Jimmy. As he stays with Richard and Rachel, he uses tools to help Richard solve detective cases.

My FAVORITE mystery anime EVER.

I have not watched much anime, but so far my favorite romantic comedy is Onegai Teacher. Another good one which is made by the same guy is Ano Natsu de Matteru.

There is an anime that I particularly liked and it's mostly a mystery anime, it's called 'Detective Conan' or 'Case Closed' for the English dubbed version.  It's exactly what aeonarial described it, it's about a teenage detective(named Kudo Shinichi in the JP version) and he gets forced-fed this drug from these "Men in black" after uncovering a shady deal. He then shrinks into a boy of a 7 year old. With his parents out of Japan, he decides to move in with his childhood friend(Mouri Ran in JP) and her inept detective father(Mouri Kougoro in JP), helping Mouri Kougoro solving crimes while finding out more about the men in black in order to regain his teenage body.

The english version 'Case Closed' only has about maybe 100 or so episodes released and I've noticed that a few episodes were skipped as well as the episodes are taking a long time to get released.  However, 'Detective Conan' anime has been in the works since early 1996(1994 for the manga) and it is still on going. I think it's at episode 648, so if anyone has had time to watch DB/Bleach/OnePiece/Naruto(ew in my opinion lol) and you can tolerate subtitles, you'll have time to watch this one. It starts out as completely mystery genre, but it evolves into a 'school of life' as the protagonist has to deal with being stuck as a elementary school kid while he still retains his intelligence and a there is definitely an element of romance as the cast of characters grow and particularly when it comes to Kudo Shinichi and his childhood friend Mouri Ran. They have romantic feelings for each other, but they are both too shy to admit it(as well as life/awkward situations/crime cases get in the way) and the way the author goes about it is so intelligent and does it on purpose that it doesn't give the readers the satisfaction, but just enough that they will be coming back for more.

It is really a treasure of an anime to watch.

My favorite anime out of those categories is Rosario + Vampire. I'm sure at least some people here are familiar with it... It's school life, romance (It also has some ridiculous panty shots and such. e_e) plus fantasy action/fighting. I only watched the first season before I quit watching so much anime but I enjoyed it a lot.

Instead of editing my old post, I'll add Puella Magi Madoka Magica as my all-time favorite mystery animu.

My favorite romantic anime would have to be Kimi ni Todoke and
Lovely Complex ( Love * Com ) . They are both really good to read
AND watch . The manga is better for both though  

My favorite romance anime would probably be Elfen Lied. For slice of life, it would be Black Rock Shooter and my favorite mystery anime is by far Higurashi.

Generally, I hate romance entirely, but I did watch a somewhat romantic anime called kodocha because it was funny and I thought the guy was cool.

i mostly like school life, there is a basketball anime called slam dunk, it is very funn and school life. 

I don't know if this counts as a school life anime, but High school of the dead is my favorite anime with students in it. I usually don't read animes that are romantic or about school. 

My Number #1 would absolutely have to be Angel beats!

-High School of The Dead (it's more zombies and boobs than actual school life lol)

-Ano Hana (One word. Tears. Tears, tears, tears. There's literally reaction videos all over youtube of people crying after watching it)

-Toradora (I absolutely loved this one. Hilarious and quite loveable characters. In my top favorites anime. You're not a true shoujo fan until you've watched this.)

-Kimi ni Todoke (It's good, made me laugh a couple of times here and there, certainly entertaining, but I just loss interest when the two lovebirds took so long to confess)

-Bakemonogatari (It's a pretty complicated anime. More talk than fighting, but when there's fighting, it's pretty explosive. Fantastic artwork. I overly enjoyed it, but um... it's certainly not for everyone.)

Saiunkoku Monogatari or Fruits Basket

Toradora is a great romance anime. I can't remember when it is I started watching it, but I remember wishing there was more when I finished the series.