Gerefan……..as Captain Swing and Nirish guy suggest all the booths on the arrival levels or anywhere in the airport apart from those on the very lowest floor (-2?) where the rail links to central Bkk are, give exactly the same poor exchange rate no matter which bank logo they have. But the booths on that lowest floor give as good a rate as any of the Surawong/silom places and more than TT in Pattaya. Start of June when I arrived I changed all my Sterling £50's at one of the Superrich booths on the airport lower floor and got just under 43baht-£, none of the Pattaya exchange booths including TT could match it.
TT is no longer even the very best in Pattaya since they opened so many branches around the city, they are obviously better than the banks but some of the small independent booths often beat them narrowly. I checked online when I was at the booths on the lower floor and compared them to TT who were at Bt42.65 compared to 42.95 at the airport. Only X-One on Surawong down from Tarntawan matched the airport booths on lowest floor. It's not a great difference but I was at the airport already and didn't have to go out of my way, and on the rate for the Sterling I had to change the difference paid for the Limo to Pattaya, and as I was met by Limo driver right after I exchanged it, the cash was safe on my person until I checked into hotel in pattaya and deposited in safe.
Updated info as at start June.