If you have luggage the change from the airport train to the MRT or BTS is easier at Phayathai than Maakasan. The Makkasan/Phetchaburi connection is a bit long and “uphill” from MRT to airport line. With one suitcase it is fine but if you have two it does become more difficult. There are also some stairs, but not many.

Of course it all depends on your budget, fitness and where you are going!