BTC is unique because it makes it easy for new wave of currency exchange, it blockchain has a unique wallet address, is not easily comprises to hackers or scammers, it benches on volume of communities members, it's God fatherism to other altcoins. Is transaction made easy and key or password individuals oriented. Bitcoin trades in a every sphere of market.
These features can be prsent too on other altcoin projects and even more advanced. But the only thing that segregate bitcoin to others are the word "decentralized" its the only one proven that can be govern since no one owns it and Satoshi gave that freedom to everyone to use of it. No CEO, no private sales, and whales but early users and buyers are the one considered whales of them but its not due to investment approach but use case of bitcoin instead.