Iron bank 300X + @ £10 - (Which is the best bonus??)

[md89]

So first time playing Iron Bank, less than 10 spins in, everything goes dark and 2 bonus's drop in, 3rd one in. 

No idea which bonus to take? So took the middle one. Whats the difference between them? The middle one is most volatile, but has more spins than the one on the left?

Either way, got it to a X50 Multiplier, and even basic wins were $1k+

Finished the bonus with $3047 - Literally the first spin, kept respinning haha.