MK3 - UMK3:
-Added Scorpion, Classic Sub-Zero, Reptile, Ermac, Mileena, Kitana, Jade, Human Smoke, Rain & Noob-Saibot (home ports)
-New stages: Scorpion's Lair, Jade's Desert, Kavern, Waterfront, Noob's Dorfen, Lost Portal
-Game wide balance changes
-2v2 Mode
-Tournament Mode
-Shao Kahn's Lost Treasures
MK11 - Aftermath:
-Adds Fujin, Sheeva and Robocop
-A couple new chapters in Story Mode
-3 Skin packs
-Possibly balance changes but nothing confirmed/advertised
Stages, friendships, stage fatalities are free.
Seems like UMK3 was the better buy. Over 20 years ago. Sad.
But you're comparing the amount of effort that goes into making new assets in this game that had hundreds of people working on it, that look amazing, with real actors, lots of voice acting, motion capture, and comparing that to the effort that would have been made in UMK3 and Trilogy, for example:
Classic Sub, Reptile, Ermac, Smoke, Rain and Noob would have simply involved John Turk posing for animations in one red costume, then they recoloured them.
Kitana, Mileena and Jade would have likewise only involved Becky Gable in one red costume doing the same.
That's 9 characters comprised of maybe one day's filming and only requiring two actors and no new voice acting. Their new additions to the story were comprised of still images and a block of text, not even FMV like in MK1's intros.
Credits of UMK3:
https://www.imdb.com/title/tt0221670/fullcredits
Credits of MK11:
https://www.igdb.com/games/mortal-kombat-11/credits
The fatalities were barely animated, the end results either cutting the sprite apart like a Monty Python animation (as opposed to the collapsing death animations 1 and 2 had) or making them all explode identically.
Sure the new levels were nice enough looking for their time, but they undoubtedly didn't require anywhere near as much work as is required in making the new ones in MK11.
Then if you take MKT assets they added, you've got MK1 levels with their dynamic animations all removed (and two deleted entirely) that didn't have their original music, the Pit bottom with floor missing at either end, the Pit 2 doesn't work because they couldn't be bothered to film new animations for it, bosses who were clearly never designed to be played with who handle like barely animated filing cabinets, among many other obviously cut corners. The biggest effort they went to with MKT was to film a new Johnny Cage due to messy business reasons.
MKT in particularly felt lazy as hell to me even back in the day, incredibly poor implementation of assets from the first two games and quite literally the quality of MK1 and 2 just felt like it had been thoroughly reduced and replaced with 4 skulls, 3 ribcages, 25 legs.
