Machine pullovers are the best, for 2 reasons: they remove the arm muscles almost entirely from the equation, unlike free weights. Secondly, they maintain constant tension. If free weights are used, do decline pullovers, which will increse the degree of ROM under tension.
Machine pullovers are a great reminder that machines can in fact be superior to free weights, and not just in 1-2 instances.
I don't think it's a matter of "filling out lats", it's just a matter of growing. Just do the standard stuff, the rest for the most part will happen through intense training, nutrition and genetics:
Choose one of each type per workout:
-Chin/pulldown
-Row of some type
-Pullover
If by filling out you mean the lower part of the lats, one of the ways is to bring the hands to the lower abs instead of upper, on row motions & pullovers.