it's mk1-gold so I assume we're including home versions

BEST:
Game: Trilogy
Warior: Chameleon
Fatality: Cyber-Smoke's Earth Bomb

WORST:
Game: MK3
Warior: N64 trilogy sub-zero (they took out the unmasked one and gave all of his powers to the classic one)
Fatality: Unanimated head rip in UMK3/trilogy

Best
Game: UMK3
Character: Sindel
Secret Character: Ermac (UMK3)
Sub Boss: Kintaro
Boss: MK3 Kahn
Fatality: Kung Lao's hat slice
Projectile: Force Ball (UMK3)
Overall Playability: UMK3

Worst
Game: MK4
Character: Scorpion
Secret Character: Noob (MK3)
Sub Boss: Goro
Boss: Shinnok
Fatality: UMK3 Scorpion's Level Pit
Projectile: Force Ball (MK2)
Overall Playability: MK4

BEST:
Game -UMK3
Character -Sub Zero
Secret Character - Reptile (MK1)
Sub-boss -Goro (MK1)
Boss -Shao Kahn (MK3)
Fatality - Cyrax's MK3 self-destruction
Projectile - Sub Zero's double freeze / ice shatter in MKMSZ
Combo - Kung Lao's spin, run in, Hp, JP, whiff dive kick, repeat cross screen for kill (MK3/UMK3/MKT)

WORST:
"ality idea"- Babalities
Game - MK2 (though I've never played MKSF)
Character - Rain
Secret Character - Meat
Sub-Boss - Kintaro
Boss - Shinnok, though he had good potential
Fatality - Mileena's suck and blow (MK2)
Projectile - Rain's MKT waterball
Combo - MK4/G - same auto combos for everyone!

BEST
Male Character: Rain
Female Character: Kitana
Hidden Character: Jade MK2
Boss: Shao Kahn
Sub-Boss: Kintaro
Special Move: Mileena's Roll
Projectile: Kitana/Jade's fans
Stage: Living Forest
Finisher: Fatalities
Fatality: Mileena's Man Eater

WORST

Character: Chameleon
Game: MK4

Best
Game: MKT
Character: Kitana
Secret Character: Jade(MKII)
Sub Boss: Kintaro
Boss: MKT Kahn
Fatality: Kung Lao's hat slice
Projectile: Jades ruturn boomerang
Overall Playability: UMK3

Worst
Game: MK1(dont get me wrong It just gets boring after about 5 matches)
Character: Jax
Secret Character: Noob (MK3)
Sub Boss: Goro
Boss: Shinnok(he did have alot of potential)
Fatality: Lui Kangs Kartwheel of doom
Projectile: Strykers double grenade(even if you hit it you will still get comboed to death)
Overall Playability: MKG(but it was funny as hell with all the glitches)

*Best

-Game: MkDA
-Character: Sonya
-Secret Character: Reptile (Mk1)
-Sub Boss: Kintaro/Motaro
-Boss: MKT Kahn
-Fatality: Too many to just pick 1.
-Projectile/Special Move: Leg Grab/Nut Punch/Kiss of death
-Overall Playability: MKDA. (I know MkU us better but I had more fun with that game)

*Worst

-Game: MK: SB and MK:SF
-Character: Mokap
-Secret Character: Noob (MK3)
-Sub Boss: Noob/Smoke crap
-Boss: Shinnok (he did have alot of potential)
-Fatality: Too many to just pick 1.
-Projectile: No clue.
-Overall Playability: MKD.

Best
Game: UMK3
Character: Ermac
Secret Character: Human Smoke (UMK3)
Sub Boss: Kintaro
Boss: MK3 Kahn
Fatality: Liu Kang's MK1 Arcade Machine Drop
Projectile: Force Ball (UMK3)
Overall Playability: UMK3

Worst
Game: MK4
Character: Kai
Secret Character: Meat
Sub Boss: Goro
Boss: Shinnok
Fatality: Stryker's Tazer
Projectile: Acid Spit (UMK3)
Overall Playability: MK4

Best
Game -Mortal kombat 2
Character - Kitana
Secret Character - Reptile MK1
Sub-boss - Kintaro
Boss -Shao Kahn MK2
Fatality -Kitana MK2 Kiss of Death and Kung Lao Vertical Split

Worst
"ality idea"- Brutalities
Game - MK4
Character - Noob Saibot or Tanya
Secret Character - Noob Saibot
Sub-Boss - Goro MK4
Boss -Shinnok MK4 - Only cause of the Shang Rip-off-ness. Story was ok.
Fatality - Not sure

Best
Game-Mortal kombat Trilogy
Character-Ermac
Secret Character-Jade(MK2)
Sub-boss-Kintaro
Boss-Shao Kahn (MK2/MKT)
Fatality-Reptile's Head Bite


Worst
"ality"-Babality
Game-MK4
Character-Scorpion
Secret Character-Noob Saibot (MK3)
Sub-Boss-Motaro
Boss-Shang Tsung(mk1)
Fatality-Mileena's Tooth Pick/Nail fatality

Best
Game- MK2
Character- Scorpion, Sub Zero and Kitana
Secret Character- Smoke (MK2)
Sub-boss- Goro (MK1, don't ask why plz)
Boss- Shao Kahn
Fatality- Liu's Dragon fatality (MK2), Kung Lao's Slice (MK2), Kitana's Kiss of Doom (MK2), Scorpion's UMK3 hell fatality, Li Mei's MKDA fatality (don't ask), Sonya's Kiss of death (MKDA), Sub Zero's head rip (MK1), Mileena's headbite fatality (MKD), all of Reptile's MK2 fatalities, Reptile's MKDA fatality and Jade's MKD fatality (the one where she throws the staff in the opponent's head). Also, Raiden's electrocution (MK1).
Stage: Dead Pool (MK2) and the Pit II
Projectile: MK2 Reptile's forceball and Kitana's fan.

Worst
"ality idea"-brutalities =(
Game- MKSF and MK3 (UMK3 improved alot thank god)
Character-Mokap (I used to hate Stryker but now Mokap's a bigger nuisance)
Secret Character- Noob Saibot from MK3
Sub-Boss-MK4 Goro
Boss-Shinnok
Fatality- Liu's uppercut fatality in MK1/MK2, Classic Subzero's censored head rip in UMK3 and Stryker's MK3 taser fatality
Stage: Scorpion's Hell (I expected it to be much better)
Projectile: Rain's fireball

Best
Game: UMK3
Character: Cyrax (MK3)
Secret Character: Smoke (MK3)
Sub-Boss: Motaro
Boss: Shao Kahn
Fatality: Cyrax's Hair Fatality

Worst
Finishing idea: Babality
Game: MK1
Character: Stryker
Sub-Boss: Shang Tsung
Boss: Shang Tsung
Fatality: Jax's Stomp

Best
Game-Mortal kombat Trilogy
Character-either Sub-Zero or Scorpion
Secret Character-Jade (MK2)
Sub-boss-Motaro (if only i could play as him in MK3/UMK3)
Boss-Shao Kahn (MK3/UMK3)
Fatality-Kung lao's MK3 spinning fatality (the first fatality i've ever done)

Worst
"ality idea"-Freindships (especially Shang tsung's MK2 Freindship)
Game-MK:SF
Character-Stryker (please, take him out of the next game, everyone apart from Stryker... or kill him after the next game, kill him off for good)
Secret Character-n00b Saibot (what a noob)(MK2)
Sub-Boss-Motaro (so... hard... can't... beat... him... must... stay... calm)
Boss-Shang Tsung (MK1) (come on, he's an old bastard)
Fatality-i like them all but if i had to pick one it'd be any fatality that was just an uppercut!

Best

-Game: MKDA
-Character: Shang Tsung
-Secret Character: Reptile
-Sub Boss: MK1 Goro
-Boss: MK3 Shao Kahn
-Fatality: no such thing
-Projectile/Special Move: Soul Steal MKDA
-Overall Playability: MKDA -got me with the 3 style system. Too broken tho'.

*Worst

-Game: MK Trilogy
-Character: Reiko
-Secret Character: Noob Saibot MK3 and MK4
-Sub Boss: Kintaro
-Boss: Shinnok
-Fatality: no such thing
-Projectile: Spear without Come here!
-Overall Playability: MK Trilogy

Only counting games before MK:DA

Best

-Game: UMK3
-Character: Baraka
-Secret Character: Ermac
-Sub Boss: Goro
-Boss: MK3 Shao Kahn
-Fatality: Hard to choose
-Projectile/Special Move: Ice Clone (Sub-Zero)
-Overall Playability: UMK3

*Worst

-Game: MK: Conquest
-Character: Jarek
-Secret Character: None
-Sub Boss: Motaro
-Boss: Shinnok
-Fatality: Hard to choose
-Projectile/Special Move: Cyrax's Green Net
-Overall Playability: MK: Conquest

Best Game-UMK3-MKT
Best Character- Sub-Zero
Best fatality-Sub-Zero's MKD alternative fatality
Best Costume-Scorpion's Alternative MKD costume
Best Boss-Shao Kahn
Best Sub Boss-Goro
Best Features-MKD
Best Endings-MK4

Worst Game-MK2
Worst Character-Hotaru
Worst Fatality-Li Mei's MKDA fatality
Worst Costume-MKD Liu Kang
Worst Boss-Shinnok
Worst Sub-Boss-Moloch
Worst Features-MK2
Worst Endings-MK1

best game- mk1-mk4
Best Character-johnny cage
Best fatality-barakas off of mkd
Best Costume-reptiles on mk4
Best Boss-shao khan
Best Sub Boss-Goro
Best Features-MKD
Best Endings-MK4
and i really don't have a worst