I have had several small companies and have always used QuickBooks Pro. Easy to learn and reasonable prices. I also use them for my personal bookkeeping with a simple program that is like a glorified checkbook system. The downside to this type of program is they continually try to sell you upgrades… which means “different”, which means sometimes you can’t find their new way to do something you need to to do. I still have my program from 2002 on my computer, but it no longer works because of a font problem. I keep it because about once a month an old customer from one of my defunct companies will call and I can look them up and sometimes help them out with their problems. If you are proficient with Excel, you can build your own system. However, if generating professional looking invoices, purchase orders, quotes, packing lists, statements and tax support data is your goal… get Quicken QuickBook Pro or one of the other programs.