Which top tech to R4 ?

DIETY

Who do i Rank 4 ? I mostly want to rank among bastion , prowler or fant . If you all wanna suggest one among those 3 please recommend which one .

Zeraphan

Jack was my first tech r4 and I do not regret that at all. I just got Bastion this week and took him straight to r4, but have not used him much yet. FAntman is amazing, mine is r3. I do not know that he gets as much as a boost going to r4 as others do.