This is NOT intended as a "My pairings are better then your's" Shipping war, this intended as a fun little list and discussion. Crack pairings are also allowed XD. Keep in Mind that I don't mind or hate other pairings that are not the ones on this list, these are just the ones I like the most.

My favorite Hetero Pairings:
SoraxKairi
TerraxAqua
RoxasxNamine
RikuxYuffie
RoxasxXion
DemyxXNamine
ZexionxXion
MarluxiaxLarxene
AxelxLarxene
DemyxxLarxene
LeonxAerith
HaynerxOllete

Favorite Shounene-Ai and Shoujo-Ai Pairings
AxelxRoxas
XaldinxDemyx
XigbarxLuxord
DemyxxZexion
ZexionxRoxas
YuffiexKairi

Hm, this looks interesting.

My favorite Hetero Pairings:
Sora/Kairi
Roxas/Namine
Terra/Aqua
Ven/Aqua
Roxas/Xion
Axel/Larxene
Demyx/Larxene
Leon/Aerith
Ven/Snow White (Crack)
Terra/Aurora (Crack)

Favorite Shounen-Ai/Shoujo-Ai Pairings
Larxene/Namine
Kairi/Namine
Xion/Namine
Larxene/Xion
Ollete/Kairi
Aqua/Cinderella (Crack)
Aqua/Larxene (Crack)
Aqua/Kairi (Present-day, since Aqua doesn't seem to have aged) (Crack)
Aqua/Namine (Crack)

Oooh! Didn't know people still post here. =P

Straight pairings:
Terra/Aqua
Roxas/Xion
Axel/Larxene
Marluxia/Larxene
Demyx/Larxene
Zexion/Larxene

Yuri:
Aqua/Larxene (could've had an encounter with one another in the Realm of Darkness one lonely night.....*ahem*)
Larxene/Namine
Namine/Kairi/Ollete
Xion/Larxene
Xion/Namine
Aqua/Xion
Aqua/Aqua
Larxene/Larxene clone

Yaoi:
Demyx/Zexion (That's....pretty much it....)

Hmm. o 3o;
Hetero Pairings
Sora/Kairi
Riku/Xion
Roxas/Namine
Vanitas/Xion (My most Favourite One. )
Terra/Aqua
Zexion/Xion
Axel/Larxene
Marluxia/Larxene
Shounen Ai
Axel/Roxas (typical I know)
Demyx/Zexion (also typical)
Demyx/Saix ( Saix-Puppy )
Axel/Sora (o 3o; It could happen... since Roxas is Sora and Sora is Roxas. XD)
Hayner/Roxas (Damn you, FanFiction.Net! D:< )
Hayner/Seifer (Bloody Fan Fictions on DeviantArt. Ah... Irukx... = w =;; ))
Yaoi
Axel/Roxas
Marluxia/Vexen
Demyx/Zexion
Axel/Sora (Damn you FanFiction.net. D: )
Brotherly/Sisterly/Parental/you get the point/Non-Sexual
Axel/Roxas (Brotherly. Axel = Big Brother)
Terra/Ventus (Brotherly. Terra = Big Brother)
Axel/Sora (Brotherly / Parental. Axel = Big Brother / Father )
Ventus/Ienzo (Brotherly. Ienzo = Little Brother)
Zexion/Ienzo (Brotherly. Zexion = Big Brother)
Leon/Sora (Parental / Brotherly. Leon = Father / Big Brother)
Cloud/Roxas (Parental. Cloud = Father )

SoraXKairi

RoxasXNamine

RikuxXion

LeaXRikku (FFX)

AquaXTerra

Let's see now: Roxas x Xion, Sora x Namine, Sora x Kairi, Sora x Alice (crack), Sora x Yuffie (crack), Sora x Quorra (crack), Hades x Maleficent (crack if you wish), Terra x Cinderella (crack), Xaldin x Belle (crack), Frollo x Aerith (crack), Terra x Aqua, Roxas x Oletta (crack?), Cloud x Tifa, Aqua x Zack (crack?), Riku x Jasmine (crack). I guess that's it for now. No Yaoi or Yuri pairings and most are crack pairings.