could you enter the ranking of the best 30?
You can rank them using different criteria.
Probably the most natural way would be to rank them by volume (in fact, CoinMarketCap.com does that already for us).
Here are the first 10:
Source: coinmarketcapYou can check the full top 30 or top 100 list on their site.
https://coinmarketcap.com/rankings/exchanges/The list is based on 24 hours Adjusted Volume.
Adjusted Volume - Volume from spot markets excluding markets with no fees and transaction mining