Because I just had to know, I used cheat engine and the fightcade emulator to go through all supers for all characters and test how far each launched the opponent into the air. The two that were the clear leaders were Makoto SA1 and Ryu SA2. Here’s the head-to-head comparison:
Ground to ground: 338 (constant)
Akuma in air vs grounded opponent: 280 (constant)
Akuma grounded vs. jumping opponent: 367
Air to air: 355
At first I thought the difference in the last 2 was because you get 2 extra hits while grounded, but you get more height if you start when the opponent’s high enough for the first two hits to whiff anyway. Weird.