If it is actually hit, yes Tsukuyomi is more deadlier. But as a whole, I would say frog song is better. Tsukuyomi is a MS technique which means it takes up a lot of chakara, and I still dont think it can be used on multiple opponents like frog song can. Plus, once you have succesfully been put in a genjutsu in a 1 on 1 situation, chances are the person will kill you.how is it deadlier than tsukyomi? it has been the only genjutsu to be clearly explained as the only genjutsu which will:: 1. alter time - 2. kill the person caught under it almost immediately.
JUST because frog song can hit mutiple targets, doesn't make it deadlier than a genjutsu that actually KILLS... in a second!