If we are talking about high-frequency trading as a full-fledged activity, then CEX is much better and more convenient for this activity.
It's also a lot cheaper (in terms of transaction fees), because you don't need escrow or atomic swaps' fees. If I'm not mistaken centralized exchanges don't take commission when you want to, say, trade bitcoin for ethereum.
The use of exchanges is not limited to bitcoin alone.
Unless you're not a gambler of course, and just want cryptocurrency to spend it. Which, in this case, I think bitcoin is your best choice.