Using regular dual band means the AP will broadcast beacons on both bands and will respond with probe responses to probe requests coming from their respective band. So the client can choose which band it will join the AP.
Dual band with bandsteering adds a little intelligence to the AP. The AP will detect if a client has sent a probe request on the 5 GHz band. If the client would after that send a probe request on the 2.4 GHz band the AP will not answer it causing the Wi-Fi client to think the SSID is only available on the 5 GHz band and join it.
If your environment has all modern laptops and modern smartphones you'll be likely to have success using the bandsteering function. However when running AP's for IoT devices you could have a certain device that will have trouble finding the SSID and thus failing connection.
So my 2 cents: depending on your environment you may try to use the bandsteering but if you see some devices that are important failing because of it, move back to regular dual band. You also have the ability to change this option per RF profile and thus per AP. So if you have an office area and a warehouse/production area you could keep the bandsteering only in the office area.