Bent over BB rows are great, both parallel to the floor or almost completly upright

However T bar also has its place

The key with back is actually pulling with ur back and not ur biceps

Keep chest high, pull shoulders back, lead with the elbows

For the best lat contraction bend over slightly and pull the bar low into ur waist, remember to retraact ur shoulders

For upper back bend over more and row the bar above the belly button