The best exercise for the back

[Sergio]

For me, I have some doubt between the chins or the bent over BB rowing.  But I have begun doing chins since three weeks looking into more back development witouth lower back injurie in the rows due to heavy training.  If you said chins, what version do you prefer:  pronation or supination?

[Mark Mills]

I said chins because of their safety and that they are a bodyweight exercise that anyone can do most anywhere. I do them underhand or parallel grip. My next choice would be the Nautilus pullover but, obviously, not every one has that machine. Here's Viator chinning....

[Sergio]

Very good pic, Mark.  I use that reverse grip and width when I do chins.  The wide gripe over hand grip is too hard for the shoulders and impossible to do for me. 

[Marko]

Dead lifts, rowings and chins, that is all that you ever need   

[Steff]

I was on my way to choose other but since I guess that the Gironda sternum chin counts as chins(duh)
I stuck with it.
If I could choose a third or forth exercise it would be deadlifts and Gironda's long pull.