What is the strongest form of ownership?

What is the most secure and undeniable form of ownership that exists today? Is it a tangible asset like a house or car, or is it something more intangible, like digital assets in the form of cryptocurrencies? Could it be argued that with the advent of blockchain technology, ownership of digital assets is now stronger and more verifiable than ever before? And if so, what are the implications for traditional ownership models and the future of finance?