One thing to note: aliexpress sells 165 carbon cranks with 29mm spindles, mostly, not 24mm. All else equal, if you want that, get a T47, because BB86 should not take spindles wider than 24mm.
My own frame is BB86 w a 24mm spindle and 170 carbon cranks. That SKU doesnt exist in 165, so i'm kind of stuck, because i refuse to pay 300 odd $ for an OEM / Chinese carbon crankset. I can do 150, but not 300.
More simply: T47 gives you more crank options.