There is no specific business that is "the best". Go/do what you are passionate about and try to make a buisiness out of it. e.g if you have skills with graphic design than open a shop that specializes in gfx for thread or web design. What I personaly see as being the most profitable business to go into at the moment is social mediums. SM is probably the most active section left on forum korner and is constantly updating. What you choose to do within the sub section of social mediums is completly up to you, you just need to decide what intrests you the most. You can experement with building accounts. You can try programs like mass checkers to find original names. Etc. The main thing you as a distributer need to establish is getting good connects. Theses connects should be other big sellers on forums that offer you good deals on their murchandise so you are able to have the best profit margin. The user Joint and I are currently writing a book on online business within forums and will be out shortly, I highly recommend you check it when it comes out. Hope this helped
Go with the business you know or you will have to pay someone to do the work. Start small but dream big. Invest in good design and good hosting also so you can attract people and retain them. Good luck...