Srixon Z545 & Z355 irons are more for the average golfers whom needs to elevate the ball flight .
Bridgestone J40, J40 combo is for Mid handicap to professional golfers.
It really depending on what you're looking for. If you want higher ball flight, Srixon would be a better choice of the 2.
Of course we all know the properly fitted golf shaft is the key to better ball striking.