Apples and oranges. Lewis was lighter, could be fired like a rifle, limited magazine capacity. Vickers was heavy, required a mount, belt fed, no limit to number of cartridges.
there is no definite answer to this, because everyone shoots different. (ther is no median) meaning a perfect shooter. but, In my opinion i like my Tokyo Marui Vsr-10 with my 6.01mm tightbore barrel...