Dan18, so true.
Have a longer ROM with the overhead chin. And the old idea of a body moving in space requires more supporting muscle involvement, may be somewhat true. Much less stress on the lower back, hard to cheat on the chin and it can be used as a power exercise. With positive or negative chins, huge weight can be handled. Extra wide grips tend to give a better stretch and hit the posterior delts very well. Personal choice; would prefer chins over pulldown type machines. One arm chins build impressive backs, grips and strength. both versions hit the ab's quite well.
Regular BB rows have a shorter ROM. Can pull to the lower abs or with a wider grip, pull to the mid to upper chest, and work the posterior delts and inner sections of the traps, all the while still calling on the lat's for their share of work. Rows work the lower back strongly, as they also work the hams. The medium to close curl grip seems to be a favorite of some very large and strong men and is an exercise worth exploring.
Personal view; I never got the results I wanted from DB one arm rows. Some swear by them and good for them. Just did not do it for me.
Both are effective movements, and really can't say which one is better than the other. May depend a lot on the selected hand/grip position one would work with. Even a few inches difference in grip (over/under/wide/narrow/etc), in either exercise, could make a world of difference as to how much positive results you may get.
Give each a equal fair shot. Suggest using both in a serious back workout.
Might suggest, as a basic back workout:
1...pullovers
2...chins
3...BB rows
4...BB Shrugs
Good Luck.
