Agree, Supra is an OK/nice looking car, C7 is a Wow! looking car. And if you spent £55k on a new UK 2020 spec car, you're gonna feel a bit upset at missing out on all the changes and improvements they are making on the 2021 model year cars. Nice used C7 please for that money.
I dare say that the depreciation on a used C7 is a lot more glacial than on a new Toyota (BMW). If they do ever bring a manual trans out for the Toyota, that will throw another spanner in the works. As you say, the changes for the 2021 model year are substantial and will impact used values. I've not seen a Supra in the flesh, but I find it borderline ugly from some angles. The C7 is a looker in comparison.