i dont really know what you mean by mature.
were as it has nudity but it isn't about it. or like ... yea :\

either way, based on the romance types you listed, i can suggest

Clannad
toradora
onegai sensei
lovely complex(this one is romance but mainly comedy.)
kaichou wa maid-sama
kimi ni todoke
karin(my first anime, kind of childish romance)

if you want an anime that i think everyone should watch,
watch: angel beats.
it has some action but it is more plot than action.
and i would have to say my top1 or 2

i also know some pretty good feature length movies
the girl who leapt through time
eden of the east(starts with like 13ish episode series and then 2 movies)

thats all i can think of for now, if you didn't want just romances well i do know some others that aren't but i just went with what you posted if you have any questions you can pm me i'll be glad to assist.

Densetsu no Yuusha no Densetsu 9/10 was really good, Although why no fucking ending?!

Hanbun No Tsuki Ga Noboru Sora 8/10 wasn't to bad for a short 6 ep series i enjoyed it and the ending was nice even though you feel sad about the outcome of the future

we need a s2 !

iso another magic show phantom was just a emotional rollercoaster.

Gosick

When I first watched it I was expecting when it said "Mystery" to be a little more like chaos;head , However it really wasn't, It really was completely different from my tastes however the last few episodes were actually epic and worth it all in the end

Liked it 7/10 , Even though it really wasn't what I expected.

Now it's time to watch something gorey/actiony/ or horrorey

watched the first season of Kami Nomi Zo Shiru Sekai ( the world god only knows ) 8/10 was pretty good and i lol'd at the parody's of other animes.
but the song at the end of the last ep was crazy i was SRS! but i lol'd it off.

watching s2 now

naruto is unbelievably long O.o

still watching naruto shippuden but on episode 99 atm so still have 130+ videos till i catch up to new ones or atleast i think it's a ongoing series

well you have awhile to go yet but just w8 you hit the PAIN vs NARUTO fight and that will probably be worth it.

Gosick Was amazing the ending was fantastic, Despite some reduculous fail mystery to the show I pretty much only focused on the main characters, Was simply amazing, And I got a new character in my top
9/10 because the mystery was soso, Great show nonetheless though for romance fans.