Final Fantasy has a monopoly on this. There's not really a list I could put down as my top 5 or 10 favorites from the series.

Notable ones:
FF8 - Maybe I'm a Lion: https://www.youtube.com/watch?v=uYDT_Y6Jj5c
FF7-Cosmo Canyon https ://www.youtube.com/watch?v=1T3srk8Dkuo
FF9: Terra: https://www.youtube.com/watch?v=b2VNDrz7Sas
FF9- Pandemonium: https://www.youtube.com/watch?v=TfnNNmlqzVA
FF7- Jenova's theme: https://www.youtube.com/watch?v=--ijjuvQMW8

Pretty much any Falcom game. Each game they make has some tracks that just kick serious ass.

Ys Seven - https://www.youtube.com/watch?v=6btxeXD7dtQ  (Anyone who loves electric guitars needs to hear this)

Ys Memories of Celceta - https://www.youtube.com/watch?v=KsZUjseeG5c and https://www.youtube.com/watch?v=C4EbmjPbf5Y

Legend of Heroes: Sen no Kiseki - https://www.youtube.com/watch?v=B6Zde1VFRp8

And that's just a taste.

i love dearly beloved, can't believe i forgot to put it on my list when i made this thread

WHAT!? That's a sin punishable by death. o.o

10. Scorch n Torch - DKCTF- https://www.youtube.com/watch?v=JFP4wn0dejc
9. Nate's Theme - Uncharted - https://www.youtube.com/watch?v=kgcq_ZtqbO0
8. Metroid Prime Credits - https://www.youtube.com/watch?v=CwA3dS_1_ts
7. Main Theme - Xenoblade Chronicles - https://www.youtube.com/watch?v=nNR-wsFAfiU
6. Terra - FF6 - https://www.youtube.com/watch?v=W7RPY-oiDAQ
5. Magma Flows - Kirby Air Ride - https://www.youtube.com/watch?v=G8TggmkHNvs
4. Promised Pain - Xenosaga III - https://www.youtube.com/watch?v=FR_-v6BXFLk
3. Gerudo Valley - OoT - https://www.youtube.com/watch?v=Hy0aEj85ifY
2. Pollyanna - Mother - https://www.youtube.com/watch?v=NVcz-XAMJ7c
1. StickerBrush Symphony - Donkey Kong Country 2 - https://www.youtube.com/watch?v=FR_-v6BXFLk

Easily, FF: Crisis Core has one of my favorite soundtracks.

Those who receive protection from the stars - https://www.youtube.com/watch?v=mHs9ao9k42g&index=20&list=PLB7E86BA3D7DF6B23

Kingdom Hearts II final mix - Rage awakened - https://www.youtube.com/watch?v=aUd4-LIKusA

Many of League of Legends opening for new skins/champs/seasons. They make some sweet tunes.

Super Galaxy Rumble- https://www.youtube.com/watch?v=y_khij4EV54

Seasons 5 Start - https://www.youtube.com/watch?v=_QaQmcDPblU

double post. ignore

5. Koopa's Road (Super Mario 64): https://www.youtube.com/watch?v=a1YhYv6-_Os

4. Busutekkai (Boss 1) (Ikaruga): https://www.youtube.com/watch?v=TzjjLKttULE

3. Palace (Ys Book I & II): https://www.youtube.com/watch?v=38dR1YYulio

2. Battle #58 (Ys IV: The Dawn of Ys): https://www.youtube.com/watch?v=X9EVobxVhrU

1. Shrine of the Sun (Ys IV: The Dawn of Ys Perfect Collection): https://www.youtube.com/watch?v=2T-wNIyRRoY

Just my top 10.

1. The theme from the Super Mario 64 starting menu screen.
2. Kingdom Hearts 2 - Sanctuary
3. Portal 2 - Want You Gone
4. Portal 2 - Cara Mia
5. Sonic Adventure 2 - Live and Learn
6. Sonic Adventure 2 - It doesn't matter
7. Kingdom Hearts 1.5 HD ReMIXthingy - Musique pour la Tristesse de Xion
8. Super Mario Galaxy 2 - Puzzle Plank Galaxy
9. Super Mario 64 - Waterworld
10. Kingdom Hearts Birth By Sleep - Enter the Darkness

I'm happy to see a couple shout outs for Ys, no awesome vidoegame music list is complete without some tracks from that series.

Here's a few other awesome guitar-driven tunes that often go underlooked...

Metal Squad - Thunder Force IV (Genesis)...  https://www.youtube.com/watch?v=oTQIiIKummw

Soldier Blade - Entire OST (Turbografx 16)... https://www.youtube.com/watch?v=qUISqOwlNAs  (Skip ahead to 0:44 for the awesome Operation 1 theme).

Desert Of Despair - Ys Seven (PSP)... https://www.youtube.com/watch?v=T-xGBHMVaig

Journey To Silius - Entire OST (NES)... https://www.youtube.com/watch?v=dNCrpIL2XlY (The opening and 1st level themes are outstanding, especially for the ancient NES sound chip).

And a little techno to mix things up... Oceania - Extreme G III (GC, PS2)... https://www.youtube.com/watch?v=ECwKWbju63Y