What is the best DEXs?

I'm interested in understanding the best decentralized exchanges (DEXs) in the current market. Could you elaborate on what makes a DEX stand out from the rest? Specifically, I'm looking for insights into factors such as user-friendliness, security, liquidity, trading pairs supported, transaction speed, and cost-efficiency. Additionally, are there any emerging DEXs that are worth keeping an eye on? Your expertise in this field would be invaluable in guiding me towards making an informed decision.