Supra.
m2 comps are also great! Bay Area traffic though with a 6 speed if you went that route.
M4’s are very nice and fast as you know and the depreciation is real.
I have a DCT 135i and it’s “pretty good” on track. Not PDK level. Definitely would benefit from a trans cooler (like the e92 M3). BMS offers the deeper pan with cooking fins which I’ll add on mine after the LSD.
Congrats!!