What are the popular halloween costumes?

What is going to be popular this year on Halloween for costumes? Last year my nephews had to be power rangers. What should I expect to have to go look for at the costume shops this year?

I would say like super man and batman ....it just really depends on the age if their still young go with superman and batman and stuff like that but if their like older try the scream mask , freddy couger , jason ((ski mask )) Micheal Myers and stuff like that ....