Just play the game however, it really doesn't matter.
The IQ, RT and input lag is amazing on the 30fps mode and the IQ is still amazing on the 60fps mode but with lower input lag, then still really great IQ and RT in the RT 60fps mode and you get the input lag benefits of the perf mode.
You already told me but I forgot, what exact model display do you use, how big is it and how far do you sit from it? Depending on that answer then maybe Perf or RT Perf is the way to go.