Bromma is excellent...
...and very close to downtown Stockholm, so if they are using 30 you get a very nice approach over the city, especially on a CAVOK day like today.
Arlanda is much further away but is connected to Stockholm by a fast train so it can actually take less time from Arlanda than from Bromma, depending on traffic. Skavsta is a long drive from Stockholm and on busy days the traffic can be bad.