Sorry Cruiser Elite. I have only just spotted this. On JTair, you would be lucky to get a bottle of water, so there is no contest.
I have just spoken to Platform 28 about a Christmas booking. However before I went into the details I asked if their 3% Amex surcharge on our last visit was policy or an aberration, as we had not been charged before. They confirmed that charging a 3% surcharge on Amex is their policy, so I told them (very politely) that not paying a surcharge was ours. So we will not be at Platform 28 this year.
Fear not, though, as blackcat20 has a couple of alternatives up her sleeve.