@ljiljan02 don't you know that posting referral links/codes isn't allowed?
Is there a single exchange available where I can buy (or sell) all major cryptocurrencies (say, current top 10) in USD , and has been consistently performing better? As of now, Coinbase along with Binance is kind of my go to option, though it doesn't cover all the major currencies that I want to build a portfolio of.
You want to stay on a single exchange? This will help you find it out
https://coinmarketcap.com/exchanges/volume/24-hour/