Depending on on my bankroll, if I have a decent one then I will opt for Bonus Buy as it's easier this way. This is also what I see with online slot streamers, they buy the bonus for free spins, and that's where the huge multiplier will show, so my point is, why wait for the bonus to show through long spins if you can simply use Bonus Buy.
Bonus buy is only popular to streamer because it’s the fastest way to hit bonus feature spin to make their viewers entertained because they knew that manual spin that usually resulted to dead spin is too boring to watch.
Most of the streamers has low patience while their bankroll is just coming from the casino sponsorship that’s why they don’t have any problem spending much money on bonus buy.
Manual spin is still the best if you have tight bankroll since you can have a chance to hit huge win on fewer spins.