There are lot of exchanges in the market who are on top 10 listed here is the link try to check them out mate
https://coinmarketcap.com/exchanges/volume/24-hour/ with this you will see how many volume they in each exchangers
now its up to you on which among them is worth to use in.
He's talking about futures, not spot markets.
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Nexybit is definitely not better than what Bitmex offers. I had a look at their platform, and it seems that they are trying to do too many things at the same time, which usually isn't a sign of professionalism. Whenever platforms are doing that, they go for quantity over quality, all to attract low tier "investors/traders".
If people for whatever reason are looking for an alternative to Bitmex, then
Deribit might be your best shot. They can't compete with Bitmex in terms of volumes, but for smaller traders an alternative worth looking into.