H1B through external consultancy is Good

I have tried through company for an onsite opportunity as they are not willing to send and postponing stating that there is no opportunity in the project so I have applied through an external consultancy where my h1b got picked need a suggestions from you as I need to wait going through a company or shall I go with a consultancy if I go through a consultancy I needs to search a job after going over there could you please let me know what are the pros and cons if we go through consultancy and if you go through a company which is a better