Set Shot 5 as the base gives you that quick release (apparently release timing is actually tied to the base), and paired with the default S. Curry form gives you something that's pretty close to his real shot form.
It's not perfect (a bit too much upper body movement), but the base is the only one that gives you Steph's quick, hitchless stroke. He also doesn't get as much air as he normally does, but I've seen him hit some set shots with a smaller hop so I just pretend it's one of those shots.
The base also has him land with his right foot a bit forward like he usually does to varying degrees. A bit surprised no one's tried this base for him but it's definitely a bit more unconventional than what you'd see in the sig shots thread.
I have Curry as:
Shooting Form: S. Curry
Shot Base: Set Shot 5
Fadeaway: S. Nash
Escape Pull-Up: Elite
Runner: Guard Textbook
Free Throw: S. Nash
Dribble Pull-Up: Normal 6
Spin Jumper: Normal
Hop Jumper: Normal
Iso Crossover: Crossover 4
Iso Behind Back: Behind Back 4
Iso Spin: Spin 5
Iso Hesitation: Hesitation 3
Layup Package: Pro Guard
Feel free to improve on this but I like this combination quite a lot.