Anyway as other people mentioned, I would buy the British Flamer Squad because it is a (British) Tier II Flamethrower with four flamers and one engineer and in case your are sicko and like the Johnson, you also get some of them. I own it and like it. Depending on your love for diversity, maybe wait until they allow us to buy the Owen squad so you get Australians. Maybe also buy the Sten Mk. III squad if its on sale. Pretty cool uniforms and decent CQC.
Planes are not really good, the A13 Premium is waste of money, Mathilda is okayish but just wait for the Grant and the rest is gimmick.