Have searched about it on the net and have seen that WPA2/WPA3 is recommended, in the case of older devices n IoT.
I normally use the hotspot to share internet to other devices. They're not too old and I don't use IoT devices.
Would choosing WPA3 be better/faster for my case? Did not see much info on that or benchmarks about it?
Saw somewhere that WPA3 has more overhead because of greater encryption, but would plain WPA3 be better than the default WPA2/WPA3?
the dual wpa2/wpa3 is 'recommended' because of broader compatibility. if you don't 'need' wpa2, don't use it. if any wpa2-only devices only need basic internet (no local resources or sharing), then set up a separate one or a guest network for those and confine your 'main' one to wpa3.
Even if so, I doubt it would be any noticeable difference.
Perhaps you could try OpenSpeedTest app and compare it yourself. But keep in mind the device positions, used WiFi standard, selected speed, channel, RF bandwidth, RF band and other nearby WiFi devices will make a difference too.
Usually these are auto-selected by the devices.