I like Raidens badass samurai look!
I love all of the female alt's but especially Li Mei and Sindels

I like Sindels alt very much

For the Dudes i like Haviks as it makes him look like Skeletor.
For the "HELLO LADIES" i have to go with Mileena....especially when it comes to that nice little piece of concept art you can unlock.

Best male alt. would be Raiden, worst would be Darrius
Best female alt. would be Kira, worst would be Mileena.

Female - Jade, I love the old look.
Male - Scorpion, again I love the old look.

Female-Li Mei
Male-Havik (gotta go for the gothic look)

male- def noob smoke
female- ill go with milenna i actually didnt like Li Mei's alt at all i think her regular costume is much better

I didn't unlock all the alts...I don't know kabal's, dairou's, tanya's and ashrah's...but the rest I know so here it goes
best male alt - scorpion because it's the mix of his mk3 and mk4 outfits and sub zero , the ponytail kinda grew up on me and I almost like it more than the shredder look
worst male alt - Darrius...no comment.. =X
best female alt - jade...enough said
worst female alt - they're all cool imo

For guys Kabal's and Sub-Zero's
Woman, Mileena (even though it's not as good as her first)

mine:
best female alternate: ashrah.
i love it! i know, she is suppose to have very little skin showing but her alternate is so... concealably sexy! see-through lace on her arms, low cleavage, the raised ponytail... mmmmm.
worst female alternate: mileena.
whore, whore, whore, whore, WHORE!
best male alternate: ermac.
it is a really cool outfit, i like his primary but it is just too much like pajama's to me for some reason... but his alternate is alot better as it has more of a 'badass killer' look.
worst male alternate: kabal.
i could take it were it was just a change of clothes, but they destroyed it by changing the mask! the resperater should always be the traingle with two circles! not a huge all over the head splat!
my opinions, i think this game has actually turn me onto alternate outfits, in mk:da i only liked sonya's, johnny cage's and reptile's, this game i indeed like to sometimes alternate.

here are mine....
best male: i think the best male alt IMO is scorpion, although i dont usually play as him its an awsome costume.
worst male: i hate darrius' alt it looks really crappy and doesnt fit into MK.
best female: i love jades alt, it looks so much better than her original costume.
worst female: i would have to say sindel (but all the females have cool costumes) because old people in lack leather isnt cool.

Best Male Alt. Costume: Scorpion and Ermac: I like both of them a lot...'specially Scorpions
Worst Male Alt. Costume: Havik and Dairu: Both are really really crappy and ugly.
Best Female Alt. Costume: Ashrah and Kira: Both of them are sooooo hot.
Worst Female Alt. Costume: Sindel and Tanya: Both wanted to make me gag...when I unlocked them, I threw up in my mouth.

Best Male Alt.:Havik's.He reminds me of the Grim Reaper in that costume.
Worst Male Alt.:Bo Rai Cho.Bo Rai Cho disgusts me and this costume doesn't help.Too plain.
Best Female Alt.:All of them but Tanya's stands out the most.Very nice.
Worst Female Alt.:I like all of them but Mileena's is the worst(even though she is very sexy in that costume).Two words:BIG HO!

Female:
Best: Jade and Kira
Worst: Tanya Li Mei and Sindel (Perfer their defualts)
Male:
Best: Hotaru and Havik
Worst: Raiden

Female: Mileena, its slutty, its kinky and mysterious, its awesome! Much better than her original, and I love her original!
Male: Scorpion, gotta love the classics....

Too much hypocrites around here saying mileena atl costume is the worst.
I mean c'mon don't except me to beleive that shit. You all like it. Yes she does look like a whore but who doesn't like how a whore dresses?

There was no need for that last part I edited out of your post. Some may find it offensive. ~ TT

Best male alt: Hmmm not sure....Kobra's is the most improved look with his alt
Worst male alt: Hotaru
Best female alt: Jade- both her looks are awesome.
Worst female alt: Mileena definitely

I like most of the alts in the game.
The ones I like are:
Ashrahs
Baraka
Ermac
Jade
Kobra
Li Mei
Mileenas
Nightwolf
Raiden
Noob-Smoke
Sindel
and Tanyas.

Male: Scorpion
Male Worst: Sub-Zero
Woman: Mileena
Worst Woman: Jade

here i agree with GILAC
Male: Scorpion
Male Worst: Sub-Zero
Woman: Mileena
Worst Woman: Jade

Male: Kobra
Male Worst: Ermac (his 1st and 2nd look the same to me just no sleeves)
Woman: Sindel & Jade (Cant choose they r both awesome)
Worst Woman: Tanya ( She looks like a damn man in her alt, with those broad shoulders)

Best male: Kabal
Worst male: Dairou
Best female: Jade
Worst female: Li Mei

Best Male: Noob-Smoke (Smokes alt is quite possibly my favorite fighter look ever)
Best Female: Jade
Worst Male: Nightwolf (what the hell is with that mohawk?!?)
Worst Female: Kira (bloodrayne anybody?)

I argree