Accountants for contractors

Hi,
I am new member. I want to get a very important advice which is directly related to my future. I want to start my business as an contractor accountant especially for small businesses. There are lots of accounting software for small businesses and I have 50 to 70% knowledge about all but I think a perfect accountant have 100 % knowledge but it is not possible to get deeply information about all software in few days so I am thinking to get efficiency in the most popular for now. can you provide me the list of major small business accounting software.