At the moment, an SP101, because its inches from my hand. Assuming I have a bit of warning, a GP100 is in the same room; 4"-barrel .357 mag ballistics do trump 2.25", and the GP100 has another shot on board. Assuming the trouble comes from the direction of the street, withdrawing to the bedroom will put me in reach of my SIG P229 duty pistol, though I don't consider it an improvement on the GP100 until the sixgun needs a reload, or until it gets dark, because the SIG has a light rail. So, my answer is based on the situation at a given moment in time. As for the aforementioned blinding flash of the .357, somebody needs to buy some fresh premium duty ammo, and not use older duty ammo, or currently produced cheap ammo.