What are your top 5 on each system? Here are mine.

PS2

1. Final Fantasy X
2. Metal Gear Solid 2
3. Ico
4. GTA 3
5. Gran Turismo 3

Gamecube

1. Eternal Darkness
2. Super Monkey Ball
3. Smash Bros. Meelee
4. Pikmin
5. Waverace Bluestorm

X-Box

1. Halo
2. Jet Set Radio Future
3. Aggressive Inline
4. DoA3
5. SSX Tricky

Overall

1. Final Fantasy X
2. Metal Gear Solid
3. Eternal Darkness
4. Ico
5. Super Monkey Ball

I'll do the GCN and Xbox since I haven't played enough PS2 games to do a top 5 list.

GCN:

1. Eternal Darkness
2. Resident Evil
3. Super Monkey Ball
4. Waverace Bluestorm
5. Super Smash Bros. Melee

Xbox

1. Halo
2. Amped
3. Jet Set Radio Future
4. RalliSport Challenge
5. NFL Fever

I'll only do Gamecube. Haven't played X-box and haven't had my PS2 long enough to answer intelligently.

1. Eternal Darkness
2. Resident Evil
3. Pikmin
4. James Bond: AUF
5. Star Wars Rogue Squadron

XBOX

Halo
Max Payne
Oddworld
NFL Fever
Project Gotham Racing

XBOX

THPS3
Max Payne
NBA Inside Drive
Halo
Wreckless

Gamecube
1. Smash Bros. Melee
2. Eternal Darkness
3. Resident Evil
4. WaveRace Bluestorm
5. Star Wars: Rogue Leader

Gameboy Advance
1. Golden Sun
2. Mario Kart Super Circuit
3. Advance Wars
4. Wario Land 4
5. Super Mario World

Gamecube:

Eternal Darkness
Star Wars: Rogue Leader
Super Smash Bros: Melee
Super Monkey Ball
Resident Evil

PS2: (only had a PS2 since May, so this just reflects the games I've played.

Grand Theft Auto 3
Final Fantasy X
NCAA College Football 2003
Gran Turismo 3
Maximo

Gameboy Advance:

Castlevania Circle of the Moon
Mario Kart: Super Circuit
Super Mario Advance 2: Super Mario World
Super Mario Advance
Warioland 4

PS2

1. GTA 3
2. Baldur's Gate: Dark Alliance
3. Ace Combat 4
4. Tony Hawks 3
5. Gran Turismo 3

Gamecube

1. Super Smash Bros. Meelee
2. Super Monkey Ball
3. Star Wars: Rogue Leader
4. Pikmin
5. Resident Evil

X-Box

1. Morrowind
2. Halo
3. Jet Set Radio Future
4. Project Gotham Racing
5. Amped

Xbox

1. Halo
2. Tony Hawk Pro Skater 3
3. Jet Set Radio Future
4. Rallisport Challenge
5. Project Gotham Racing


PS2

1. Maximo
2. Jak and Daxter
3. Final Fantasy X
4. Devil May Cry
5. Grand Theft Auto 3


Gamecube

1. Star Wars: Rogue Squadron II
2. Eternal Darkness
3. Pikmin
4. ??? only three games I've liked so far...

GBA:
1 - Sonic Advance
2 - Mario Kart Advance
3 - Pinball of the Dead
4 - Super Mario Advance
5 - Advance Wars

XBOX:
1 - Halo
2 - Dead or Alive 3
3 - Crazy Taxi 3
4 - Amped
5 - NFL 2K2

(Just bought JSRF, and that will probably jump into the top 5, but havent played it enough yet..)

Dreamcast: (yes I still play it)

1 - Sonic Adventure 2
2 - Outtrigger
3 - PSO Ver 2
4 - Ooga Booga
5 - Sega Smash Pack

-Jim

Even if you only like ONE game on a system, just list the 4 others. This is about what you consider the top 5, you don't have to like them.

For example, my X-Box list. I don't even really like #3, 4, and 5 on the list, but I consider them among the best on the system from what I have played.

Xbox -
1. Morrowind
2. Halo
3. Max Payne
4. Project Gotham Racing
5. not sure

GAMECUBE
1. Star Wars: Rogue Squadron II
2. Super Smash Brothers
3. Pikmin
4. Eternal Darkness
5. Super Monkey Ball

PS2
1. Metal Gear Solid 2
2. GT3
3. Grand Theft Auto 3
4. Maximo
5. NHL 200x (not exactly platform specific)

what no PC?

top 5 PC games

Baldurs Gate 2
Jedi Knight 2
the Curse of Monkey Island
Warcraft 2
Half Life

Xbox-

1) Halo
2) World Series Baseball (The best baseball game I've ever played)
3) Jet Set Radio Future
4) Oddworld
5) NCAA Football 2003 or Max Payne

what about the old games?

Nintendo 8-Bit
1. Super Mario Brothers 3
2. FF1
3. Bubble Bobble
4. Megaman series
5. Adventure Island series

Sega CD
1. Lunar EB
2. Lunar SS
3. Shining Force CD
others all sucked

PC to 10 all time
Doom
Quake
Warcraft 2
Diablo
The Sims
Simcity
Everquest
GTA3
Warcraft 3
Need for Speed

Gamecube
Super Smash Bros.
Eternal Darkness
Pikmin
Resident Evil
Wave Race

GBA
Golden Sun
Advance Wars
Tactics Ogre
Castlevania
Mario Kart

PS2
GT3
GTA3
Shadow of Destiny

GameCube

1. Super Mario Sunshine
2. Super Smash Bros Melee
3. Pikmin
4. Eternal Darkness
5. Super Monkey Ball

PlayStation 2

1. Grand Theft Auto 3
2. Final Fantasy X International
3. Gran Turismo 3
4. Winning Eleven 6
5. Virtua Fighter 4

XBox

1. Halo
2. Jet Set Radio Future
3. Dead or Alive 3
4. Waiting for there to be a #4 and #5

I haven't played too many games but I'll list anyways!

GBA:
Tactics Ogre
Advance Wars (guess)
Golden Sun (guess)
Mario Kart (guess)
Super Robot Wars (guess)

Gamecube:
SSBM
Rogue Leader
Resident Evil (guess)
Eternal Darkness (guess)
Super Monkey Ball

Xbox:
Halo
Morrowind
NBA2k2
Fuzion Frenzy
Rallisport Challenge (guess)

The one's I listed as "guess" is basically my guess. I don't have those games, but I played some of them. Some others is just what I think could be good.

PS2
1.Grand Theft Auto 3
2.Grand Theft Auto 3
3.Grand Theft Auto 3
4.Grand Theft Auto 3
5.Grand Theft Auto 3
Nothing and i mean NOTHING comes close to this game!!!!!

XBOX
1 Morrowind
2 Jedi Starfighter
3 Blood Omen 2
4 DOA3
5 Halo

Just started play Blood Omen but love the fight scences and the blood. Great game. Found it for 17.99 used. Great deal.

Dreamcast

1. Capcom vs SNK 2
2. Marvel vs Capcom 2
3. Street Fighter 3 third strike
4. Marvel Vs Capcom

for the 5th i would have to say King of Fighter 2000 which isn't out yet(next week) but i love the arcade so i know i will love this game. They are still making great games in japan that will never be in the us like shenmue 2, capcom vs snk 2 (ps2 only in the us) and kof2000.

Dreamcast ownz all other systems in 2d fighting games

edit:

PC

1. Mame - Marvel Super Heros vs Street Figter 2(online!!)
2. Mame - Marvel vs Capcom (online!!)
3. Mame - Street Fighter Alpha 3 (online!!)
4. Mame - King of Fighters 2000 (online!!)
5. Mame - Street Fighter 2 CE (w/ rainbow hacks)

odviously i love 2d fighters

Forgot about the good ol imac

apple:
1. Warcraft 3
2. Breakout
3. Super Breakout
4. Who Wants To Be A Millionaire - 3rd Edition
5. Photoshop

PS2

1. GTA 3
2. GTA 3
3. SSX Tricky
4. Madden 2002
5. All-Star Baseball 2002

XBOX
1. Halo
2. Rallisport Challenge
3. MotoGP
4. Silent Hill 2: Restless Dreams
5. Elder Scrolls III: Morrowind

GameCube
1. Rogue Leader
2. Resident Evil
3. Pikmin
4. Super Monkey Ball
5. Super Smash Bros. Melee