If you are going to trade on a daily basis on the spot, you can only do that on high-volatility coins, but if you do that on Bitcoin with a very slim spike, you will end up losing because of the high taker and maker fees.
Usually, crypto exchanges have a 0.1% minimum taker and maker fee, plus the gap between the bid/ask is not worth it if BTC couldn't spike at least more than 2 or 3%.
Other coins are more volatile, but it's riskier than BTC because the price spike is high; it can sometimes hit 10% or more in a day.

About exchanges, I don't know what fastest way you mean, but almost all of the exchanges can execute trades instantly.
I'll mention a few of them, like Binance, OKX, and Bitget.