Need a new Neu motor

I've just sell my 1515 1Y/f and take the plunge for the 6s.
I've order a Flightpower 5000mAh, 25C, 6s, and now i hesitate between the 1515 2.5d/f and the 1515 1.5Y/s.
The Kv is realy close (1650 for the 2.5d and 1500 for the 1.5y).
The 2.5d is available in finned can but the 1.5y is only stock in smooth can.

It's for my Mugen MBX5T truggy.

Which one would you take to my place????