As you have said, it's varies individually, people might find Livecoin a scam and shitty exchange, but others makes a lot of trading there and made a lot of money.
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So it's everyone preferences and we can't categorised which one is the best because it will be very subjective.
I think we can categorise which one is the best at various level. By commun sense, users are most attracted by friendly use exchanges that ensure security and anonymity, usually decentralised ones. But most of those decentralised exchanges hasn't a significant liquidity.
However, many people choose centralised exchanges for various reasons if they don't mind submitting their personal docs. They just use the exchange as they use banks, and even use the unique address given by the exchange as their official wallets.
I find it strange that users still use exchanges that are confirmed as a scam like livecoin and yobit.