Which are the best competitors to Ethereum, and why do you think so?
(I know on top of my head that Cardano and IOTA try to challenge Ethereum,
although they still haven't proved much from my understanding?)
Recently EOS has gotten a lot of attention. It is seen that eos maintained its price during the long fall of the crypto market and it rose together with Bitcoin whiles Ethereum stayed the same. An article I read termed eos as the 'Ethereum killer'
I believe ETH's current biggest rivals are EOS and NEO. In the future I see the ADA as the most worthy opponent because they have a strong and updated coder team (you can view reports from their github). That is the natural law, the latter comes with better technology than previous products such as ETH. ETHs still have a lot of hope because they have government agencies and big corporations that are interested in their projects and the large user community is ready to support their projects.