Great feedback all! Like the tri kit itself, this often is a very personal decision. One brand fits one person well but not another. It might be worth heading to a running store to try a few one if you don’t have a good running bra that you use now.
That said, I recommend that you race in one that you have been training in. Now how it feels, what it does (support, non chaffing, etc). I have a few different types of Nike bras and some don’t chafe and some do. What I might recommend is looking at the seamless bras. They are much less likely to chafe because they lack seams! And if you want to consider wearing a bra with an underwire in it, I would practice with it in training and a shorter course race.
Sounds like you have your homework! Keep the questions and feedback coming!