Agree, there are two types of taxi drivers waiting upstairs on the arrivals level.

* the typical Thai taxi scamsters waiting for their next prey. They will enthusiastically encourage you to take their taxi. My advice is not to choose this type.

* the driver that has just dropped off a fare. This is my choice for taking a taxi. Wait until the arriving customer has gotten their bags and paid their fare, and then swoop in, confirm the destination and use of the meter, jump in, and leave the scammers behind.