Neo Geo CD can be a fun machine if you know the “right” software to get.
Loading times are a real problem only when they are not just long but also very frequent.
Unfortunately many fighting vs games suffer frequent loading times because their nature.
However these are the games I usually recommend (quality games, with fine loading times):
Beat’em up:
Sengoku 2
Mutation Nation
Shoot’em up:
Aero fighters 2/3
Last Resort
Pulstar
Twinkle Star Sprites
Viewpoint
Action:
Ninja Commando
Metal Slug 1
Magician Lord
Nam 1975
Top Hunter
Raguy
Crossed Swords 2
Racing:
Neo Driftout
Sport:
Super Sidekick 2
Baseball Star 2
Street Hoop
Windjammers
Puzzle:
Puzzle Bubble
Magical Drop 2
Fighting vs
Fatal Fury Special
World Heroes Perfect
Art of Fighting 2
Samurai Shodown 2
Real Bout Fatal Fury 2 (on the long side but the “fastest loading” of the latter fighting vs games)
Games under 55Mb load just at the boot up, after that they are “loading time” free.
Example: Magician Lord, Mutation Nation and Last Resort.
Games with size under 120-130Mb have usually very short loading times.
For NGCD I suggest to pick up only games under 220Mb.