Ethereum Q&A: Smart Contract Platforms

What is the best platform for smart contracts? What makes Ethereum interesting to you? So far, most of the platforms experimenting with smart contracts, besides Ethereum, are either still in the roadmap or early testing phases of development (i.e. federated sidechains and drivechains). Most of the so-called "third generation" blockchains have not been able to differentiate sufficiently from the first and second generation blockchains. We cannot draw very accurate conclusions without being able to compare them at scale.
When I speak about Ethereum, I am speaking more broadly than the ETH token and blockchain, but rather virtual machine-based, Turing complete, programmable blockchain for smart contracts. During the maturation of this technology, there are going to be a lot of governance missteps and security vulnerabilities because they are choosing flexibility over security in the tradeoff. Ethereum can't do what Bitcoin does. Having a robust, simple script language and conservative, reliable development is a strong differentiating factor. The biggest challenge for both Bitcoin and Ethereum moving forward is privacy.