proprietor or partnership

Proprietorship - simplest way to establish a business with least paper work, however the creditibality goes to individual proprietor only, in case of financing by bank.

partnership firm - as the name is FIRM, it is set up by two or more persons, little more paper work,  no exemption in incometax, except salary to partners, TDS provisions apply from start, change of partners invite stamp duty and registration procedure.

Company - same as partnership firm, ROC formalities are additional, strong set up for financing, audit is mandatory, change of directors are easy by share transfer. 

depending on your capital layout you can select any.