The anwer to which state is "better" depends on what you are measuring, and in turn points you to the resources you'll use to investigate that issue.  If by "better" you mean lower taxes, an accountant would be an excellent resource.  If you mean "fewer regulations," a small business development center and an attorney specializing in your industry area would certainly help.  If you mean "entrepreneurial climate." or "relevant, talented workforce" there again, the SBA or SDBC, or local business library may have that information.  A good way to go about the investigation is for you and your business partner to write out a list of the questions you have about starting a business.  You can ask them of an attorney, accountant, and other resources in New York; your partner can do the same in Massachusetts.  Once you've done the investigation, sit down together to compare your answers.