I know that there is a thread already for J-Rock, however I'm asking for a broader list. =)

Currently listening to stuff by bands like; Royz, GazettE, Jupiter, Eir Aoi, Vistlip, Anfiel, etc..

I tend to find most of my music through LMN J Music on Youtube, but it seems he hasn't uploaded in a while... =/

Any personal recommendations appreciated, =) J-Pop is fine aswell

Waaa~ that's been a long time! So my recommendations might be a bit outdated sorry! I only know the Gazette out of those you mentioned ^^'
But here they are anyway:

Jrock:
- Miyavi: Jibun kakukmeiHi no hikari sae todokanai kono basho deHorizon  
- Versailles: The Revenant Choir (the song starts after 2 mins)
- X Japan (saw them in concert, that was really the best concertI've ever been too *-*): Silent JealousyKurenaiSay Anything
- LM.C: Ghost Heart
- One OK Rock: The Beginning
- L'Arc~en~Ciel: Forbidden LoverDive to BlueJoujoushi (sorry had some trouble finding youtube links for those, so they are lives)
- Buck-Tick: Romance
- Dir en Grey: 304 Goushitsu, Hukushi No SakuraYuramekiYokan
- Nightmare: Tsuki no Hikari, Utsutsu no Yume
-Gackt: RedemptionSecret Garden

Jpop:
- Hikaru Utada: Prisoner of LoveBeautiful WorldCome back to me
- Hilcrhyme: Personal Colour
- NAO: Paper Moon

I left out the JENT jpop (KAT-TUN, NEWS,..), they nearly unfindable on youtube anyways x)

Hope it helps!
You saw X in concert?? Aw the jealousy. The nostalgia.

I haven't been active in the J-Rock/VK fandom for a while now, but some more old favorites: Girugämesh, Luna Sea, SID, Unsraw, D'espairsRay, Hyde.

Also, I second Nezumi's recommendations for Miyavi, X Japan and Dir en grey.
@devitto: haha yes, to be honest, I sometimes still can't believe I've seen them xD The atmosphere was incredible! 
I can only imagine.. I've been thinking about going to their concert in London next year. Don't know whether that will work out, though. Paris didn't. Dx
Sorry for late reply >_<
@Nezumi, I actually know quite a bit of those bands =3
Thanks for the suggestions, I'm quite liking the NAO / PaperMoon song

Gonna add some songs I kind of recommend for others to try =D

Anfiel - 『unfil』 https://youtu.be/IPPGN74d5hI
Jupiter - 「TOPAZ」https://www.youtube.com/watch?v=tNPHha8nACA
Royz - 「Emotions」 https://www.youtube.com/watch?v=y2-yaYPiX2c
DISACODE - ARCO∞IRIS https://www.youtube.com/watch?v=_lh78HpZPQA
DOLL$ BOXX - Take My Chance https://www.youtube.com/watch?v=mu2z4Uf9Tgc
Golden Bomber - Laura no Kizudarake https://youtu.be/joTSz8N7f68
Jackman - The Right Crime https://www.youtube.com/watch?v=lFktCVLw2ms

If anyone wants me to link more I don't mind, sharing is caring
I found some old music I used to listen too and thought of this thread again :P
I'll post those too, you might know them as well, but oh well :P

Jrock:
- heidi.: remusynchro
- 12012: aitai karacyclonebutterfly
- MUCC: Fuzzshion, (omg can't belive I forgot them in my previous list *o*)
- Abingdon Boys School: strength
- Anna Tsuchiya: Kuroi Namida (from movie Nana)
- Art Cube: Suna no hana
- ayabie: aitakute, theme
- BREAKERZ: miss mysteryreal love
- D: ouka saki some ni keri
- Kaggra,: utakata
- Kelun: utari
- KRA: Yell
- An Cafe: cherry saku yuuki
- Megamasso: chimesm of beauty
- Vidoll: Cloud

Jpop:
- Ai Otsuka: Planatarium (actually ost of 1 litre of tears or Hana Yori Dango if I remember well..?)
- Ayako Ikeda: prism
- Ikimono gakari: ima hashiridaseba
- Remioromen: Konayuki
- Stereopony: hitohira no hanabiratsukiakari no michishirube
- YUI: Gloria
- Youhna: Houkiboshi (she's actually Korean but it's her jpop career that made her famous or something)

Something else entirely and you are not likely to have missed that lol:
Kyary Pamyu Pamyu: PONPONPON

There, that's it. I'm done now :P

Hope you find something to your liking again :3