What sand is best for a sandbox?

In the realm of cryptocurrency and finance, we often encounter various platforms and frameworks that act as the "sandbox" for our investments and strategies. So, I must ask, "What type of 'sand' is best for a financial sandbox?" Is it the traditional, well-established exchanges that offer stability and reliability? Or perhaps the innovative, decentralized platforms that promise transparency and flexibility? Each has its unique characteristics, much like different types of sand: some are soft and easy to mold, while others are harder and more durable. Understanding the pros and cons of each will help us determine which 'sand' best suits our financial sandbox.