GHQ is so much better than Bonus stage.
GHQ seems to always give eigther:
a) Triple Exp chance 18%
b) Triple Chance 38% Chance of SR-girl form a trippel chance spin seems to be the same as anywhere else.
c) Triple Pero 13%
d) Triple Gift 28%
e) No-triple 3%

Cost per spin 20 stamina
Exp: 15
Pero: 60

Updated based on 130 spins

But to finish all the Chance missions a players need 3x Chance 18 times.
On avaridge this takes 18 /0.38 = 48 spins = 960 stamina. So a player with max 240 stamina have to lock in 4 time to have a fair chance to finish thise missions even if he focus on thise missions all the time. At bonus stage chance for finishing the chance missinons seem even lower.