If the machine is working the lats as well as 1-arms stay with it; sometimes machines are better. Or mix it up with:
-1-arm free weight rows using straps, using a t-bar or holding onto the very end of a BB.
-1-arm pulley rows.
-2-handed T-bar or BB rows. If you want to support your back as with 1-arm rows, do BB rows lying face down on a bench.
-Pre-exhaust the lats on machines/free weights, after which the weight used on 1-arm rows should decrease.