If each platform had 1 defining shmup what would it be?

[benf]

For SNES I'd pick Phalanx.

[scarper]

GBC: Magical Chase
GB: Chikyuu Kaihou Gun ZAS
NES: 1943
SCD: Lords of Thunder
TG16: Aero Blasters

Honorable Mention:
N64: The final boss in Kirby 64 The Crystal Shards

[iwaspromisedjetpacks]

These are only my opinions..

Neo Geo - Pulstar
NES - Zanac
SMS -Power Strike 2
Wonderswan - Judgement Silversword
Genesis - MUSHA
SNES - Macross Scrambled Valkyrie
Saturn - Radiant Silvergun
Dreamcast - Giga Wing 2
GBA - Iridion II
PS1 - R-Type Delta

[elmagicochrisg]

Mega Man party above me...

[Mothman Prophecies]

These would define x system.

NES - Lifeforce
SNES - Gradius III
Master System - Fantasy Zone!
Genesis - Thunder Force IV
Saturn - Radiant Silvergun
GB - Solar Striker
Dreamcast - Ikaruga
PS1 - Einhander

If you want my honest opinion then..

NES - Recca
SNES - U.N. Squadron/Macross Scrambled Valkyrie
Master System - Power Strike II
Genesis - MUSHA
Saturn - Batsugun
GB - Chikyuu Kaihou Gun ZAS
Dreamcast - Giga Wing 2
PS1 - Harmful Park

[CRTGAMER]

I see all the lists of everyone's favorites. So what draws one into a certain title? How about a sentence or two as the reason why?

PS2 Raiden III
This one has a very unique feature. Ever play Cookie and Cream? What does this have to do with Raiden III? Well I love different types of games with a unique game play, such as Twin Stick games. How about controlling both Player One and Player Two ships with one controller!

Left Analog, L1 and L2 = Player One
Right Analog, R1 and R2 = Player Two

For game mode Press ∆
You can work both ships, this so much better then random good luck bullet hell shumps. Some real skill involved here! I do miss the giant crawling crab tanks from PS1 Raiden Project though.