Solely box office wise
Raju Hirani > Rohit Shetty > Sanjay Leela Bhansali
Rajkumar Hirani = Sanjay Leela Bhansali >>>> Rohit Shetty
The problem is Rajkumar Hirani's last two films remained his one of the weakest & the weakest works.
Similarly, SLB's work this decade ranged from What [Ram-Leela] to well good [Bajirao Mastani] to meh [Padmaavat].
Even then, they're miles ahead, better compared to Rohit Shetty.
Since you asked difficulty of genre wise,
Rajkumar Hirani has a style & he picks humour [not slapstick comedy or commercial comedy] to narrate his stories. So in that way he has basically made his films on the same note ever since Munna Bhai to Sanju. Not that it is a bad thing, as he is making his style of filmmaking as a genre by itself & it is not easy for others to mimic it.
In a way, SLB is the one inspite of "love ballads", is trying to explore. But this decade too it's about grandness than the screenplay for SLB. Hopefully he will emerge better sooner.
Rohit Shetty is only dwindling between comedy & action-comedy. He hasn't made a true action film for a while. Infact Zameen & Singham Returns were the only proper action-dramas he made. So yet to explore his direction skills in different genres. Comedy is not an easy genre, despite mediocre films, brownie points for churning out blockbusters in that genre. But, Raju Hirani's choice of humour is more long lasting than Rohit Shetty's.