I've always liked television from the 90s but I've never watched any jdramas from then minus Kindaichi Case Files. I would really appreciate if I could get some recs even if they're a bit obscure. I don't have any particular genre in mind and I'm up for anything but I guess for a general idea dramas about family, youth/school, romance, or mysteries? (not all together but if there's one that has all those genres packed into one then that's great) Plus if there's any /classics/ you think I should watch please tell.

I'm up for things from the early 2000s (pre-2005) as well. 

you should watch the original gto : http://mydramalist.com/116-gto
if youre into romcom i suggest Dekichatta Kekkon
school drama : Dragon Zakura
Kimi to Ita Mirai no Tame ni
Aishiteiru to Ittekure

Early 2000s:
Satorare
Remote
Sayonara, Ozu Sensei
Tiger & Dragon


I second everything that has been added and recommend

90s:
Tokyo Love Story (romance)
Hitotsu Yane no Shita (family)
Ice World (romance, thriller)
Over Time (romance)
Long Vacation (romance)
With Love (romance)
Hitorigurashi (romance)

Early 2000s (until 2005):
The Queen's Classroom (school, mystery)
Nobuta wo Produce (school, friendship)
Stand Up!! (school, friendship)
Gokusen (school)
Koi no Chikara (office, romance)
Long Love Letter (sci fi, school, romance)
Kimi wa Petto (romance)
Manhattan Love Story (comedy)
Beauty or the Beast (office)

Be forewarned that since it's Japanese drama, happy ending is not guaranteed even for romance dramas. And of all the dramas I recommend above, apart from Gokusen and maybe Manhattan Love Story (which is bonkers by design), I think none has overacting that people often associate with Japanese dramas.
From the 90's:

GTO (youth/school)

From 2000 - 2005:

Summer Snow (romance)
Taiyou no Kisetsu (romance)
Gokusen (youth/school)
Pride (romance)
Suna no Utsuwa (mystery)
Sekai no Chuushin de, Ai wo Sakebu (romance/drama)
Nobuta Wo Produce (youth/school)
1 Litre no Namida (must watch!!) (youth/school/family/romance)
Dragon Zakura (youth/school)
H2 (youth/school/romance)
Hana Yori Dango (romance/school)
Aishiteiru to Itte Kure : by far one of the best romance in Jdramaland, and it's from the 90s
Thank you all for these recs I will check them out!
90s:
Ningen Shikkaku
Seija No Koushin
GTO
Kamisama Mou Sukoshi Dake
Yume No California
Ao no Jidai
Kou Kou Kyoushi
Kono yo no Hate (this wasn't my favorite but you might like it)

2000s (pre 2005):
Ikebukuro West Gate Park
Gokusen
Ningen no Shomei
Long Love Letter
Kou Kou Kyoushi 2003 version
Nobuta Wo Produce (2005, definitely worth watching!)
Densha Otoko (2005 so it's borderline)

Movies:
Go
Kamikaze Girls
Not 90s but check out some Takuya Kimura dramas, like "Good Luck!" (weird title for premise of the show lol)