Who are Ethereum competitors?

As a keen observer of the cryptocurrency landscape, I'm curious to delve deeper into the competitive arena surrounding Ethereum. Could you elaborate on some of the key rivals that Ethereum faces in the smart contract and decentralized application space? I'm particularly interested in understanding how these competitors differentiate themselves from Ethereum, whether it's through their technical architecture, scalability solutions, or their approach to governance and community engagement. Additionally, I'd like to know if there are any emerging players that are gaining significant traction and posing a threat to Ethereum's dominance in this rapidly evolving industry.