It's hard to call any one type of business "the best." So much depends on the individual entrepreneur -- that person's skills, background, likes and dislikes, available seed money, and so on.
Here are some ideas of promising businesses that can be run from home. These require very little startup cash. They are within reach of large numbers of entrepreneurs without the need for extraordinary expertise:
consulting requires little in the way of startup money and can be tailored to suit the entrepreneur's skills. If you are going to be a consultant, remember that the bigger ticket your services, the longer a sales cycle you will have. Try to have some offerings that can be sold for under $100 (e.g., copy editing services or drafting press releases), in addition to big ticket engagements, in order to get your cash flow going sooner.
(2) Pet related businesses:
pet related products and services are hot right now. Many of these kinds of businesses can be started from home and run from home indefinitely or until they outgrow the basement or the garage. Think about homemade doggie treats, or pet clothing such as bandanas or beaded collars, etc. Even dog grooming services can be started and run from home for a while.
(3) eBay selling:
selling on eBay continues to be lucrative for many entrepreneurs. Start by selling stuff you have lying around the attic or that you pick up inexpensively from garage sales, and then grow from there. You can become a specialty seller if you are knowledgeable in a specialty area, such as a certain type of collectible. Check the eBay hot sellers, too. For instance, certain kinds of used blue jeans, old toys or vintage holiday decorations can bring a premium -- stuff you might otherwise have thrown away. One advantage to an eBay business is that you can start bringing money in the door within 2 weeks, assuming you have some stuff around the house to sell.
(4) Internet sites:
Internet sites continue to be nice niches for people. You can set up an inexpensive website or even a free blog, start posting content on a subject, and then add some Google AdSense text ads and also become an affiliate seller. If you work hard at it and show some marketing savvy, you can make a nice side income, especially if you run multiple sites. However, this kind of business takes time to develop and drive traffic to it, so make sure you can cover your living expenses for the first six months, or start this as a side business in the evenings, while you are still employed elsewhere. Because there are so many Internet businesses already, the best thing is to find a niche topic that is underserved, and start writing about it. Stick with it and pretty soon you will be perceived as the expert in that niche.
(5) Landscaping/Snow removal businesses:
In my area, at least, there always is a need for landscaping services, especially those that will take on smaller jobs or cut grass, do spring and fall clean-up, pressure-wash decks, and so on. In the winter time, they often couple their services with snow plowing, and shovelling walks. While some equipment is required to get started, often it is no more than the equipment you already have available for personal use, such as a lawnmower, leaf blower, riding mower with snow plow blade, etc. You can use the money you earn to buy more and better equipment, and hire helpers. Attract business by placing ads on supermarket bulletin boards and in local green sheets or similar local papers that accept classifieds. Or if you happen to be in an area served by Craig's List, try that. Alternative:
For indoor types, there is always the maid/cleaning service that requires just a bucket, mop, broom and some cleaning utensils.
Hope this helps!