What is the best preparation for business?

Business is a broad category, so you really need to think about what it means to you. Do you want to be a personal business owner or work in a Fortune 100 international corporation? Do you want to manage a team of people, lead an organization, or contribute at an individual level to the companies goals? These are types of questions you should consider as you pick your path. Different paths can provide better preparation. As a base level though, you should develop a few solid skills that are often best provided in a university setting.
Understand how to learn fast. Being agile and a quick study help you adapt to any situation. Knowing how to find information and learn are essential to success at any company. It means you can solve a more diverse set of problems using tactics and ideas others have developed. Innovation is often considered applying old knowledge to a new situation in a novel way. Being able to learn is an essential skill
Practice solving difficult challenges. Engineers often do well in large companies. Their math skills help in financials, stats, and advance analytics. More important is the intense training on how to compartmentalize problems in a way that enable them to be solved. Engineering can be a great path to join a company and manage businesses. I work with many people in different business disciplines with engineering backgrounds. They develop strategy, run supply chains, build sales operations organizations, run IT organizations, and other diverse fields. Engineering can be a great discipline to help a nascent business career.
Most businesses today operate internationally. Understanding how to trade, implications, and other cultures can be important for even a small business startup. Many small companies import product from China, India or other markets. Having studies around international trade and business can be essential skills depending on the path you want to head.
If you want to startup your own business, it is still a smart move to be well grounded in financial analysis. Many startups struggle to understand how to tap into financial resources and manage their cashflow. Financial techniques can make or break your new business. Learning about finance and marketing in a business degree program can help you build your personal business.

The net of this, is you need to think about what type of business career interest you. Following your passions is usually the best path. You need to want to work in an area that is enjoyable and brings out your best qualities. Having that extra drive to succeed is critical in any business career. Building the skills to understand information, learn, addressing your customers, and company financials are essential skills. It's possible to learn these outside of a college environment. It can also be a quick 4 year accelerator meeting people with common goals in a university program. Like many things, college is what you put into it.