Mine is for the Visual Kei band, D. My best of list merely contains my personal favorite songs, without other considerations.
1. Yami Yori Kurai Doukoku no Acapella to bara yori akai jounetsu no aria
2. Gate to the Sky
3. Der Konig Der Dunkelheit
4. Angelic Blue
5. Dearest You
6. Akumu Kurai
7. Ouka Saki Some ni Keri
8. Sleeper
9. Gikyou Souden
10. Neo Japanesque
Mainly for me Yami Yori~ is number one because it was one of the first songs I heard by them and I still listen to it all the time. Gate to the Sky takes second for me because I heard Yami Yori~ right before it, and thought it had an excellent opening to a song. Gate to the Sky's opening is even better to me, and I was amazed. The third favorite is Der Konig Der Dunkelheit for the gothic melody of the music. The track is great, completely solid and the PV is pretty awesome to boot.
The other 7, I won't rant on about. They're all great tracks to me, and I listen to them all quite frequently. The last 7 are in no particular order, but I do love them each very much.
Edit: I know my posting doesn't follow the exact ordering of the thread, sorry. I plan on posting another one more fleshed out sometime soon.