Cardano is a unique cryptocurrency because it was built from scratch. The use of Haskell language and the Ouroboros protocol gives it an edge in security over NEO.
It is also worth noting that the project is actively developing and has already established cooperation with well-known blockchain startups, including Bancor, Coindash and Agrello. The Chinese blockchain startup Red Pulse has announced the creation of a platform for financial research, which will be built on the NEO 2.0 smart contract system. Also, in cooperation with the NEO project, an operating system on the blockchain called Elastos is being developed. According to the developers, it is designed tostudy the technological value of the use of blockchain applications in new Internet operating systems and further development of Smart Economy".
I choose NEO.