It depends on the effect you are looking for with the seated row. One of my co-workers at the gym I train in likes to nice and slowly go all the way forward then extend at the hip and row the weight in. He trained me once and I thought this method fucking blew. There was way too much stress on the lower back, and I’m trying to do a row using my fucking lats not do some sort of aborted romanian deadlift cable row shit.
The best way to thoroughly work the lats is to keep a slight lean forward with your lower back in neutral. You have a great range of motion and really hit the lats nice and solid. It gets to a certain point where it is very hard to increase the weight using this form however and you may want to straighten up to neutral. In my opinion when you start leaning back doing a seated row you are cutting short your range of motion while at the same time turning the exercise into more of a shrug. Many people love this, thinking the extra weight you can use is more than worth sacrificing perfect form. I think the lats and the back would be the same if not better with less weight and better form…