I wouldn’t stop at “just” one fan. Don’t mess around with little weedy desk fans, you need some fairly serious air moving power if you’re going to be working hard. It also depends how much you are willing to spend.
I’ve got a cheapish screwfix one on a smart plug that works great, and a wahoo headwind that is similar but betterer in terms of features – more focussed airflow to hit just your body, and ability to control it via phone app or via heart rate. I’m keeping both for extreme summer days when you just want as much airflow as you can get.
I wouldn’t recommend one or the other, it just depends on your budget.