Accurate #7 would be a sound choice. Here's teh company profile of it.
Accurate No. 7 is an intermediate burning, double-base, spherical powder suitable for a wide range of handgun calibers. No. 7 is an excellent choice for high performance semi-auto handguns such as the 357 Sig, 38 Super, and 40 S&W. No. 7 is also a cost effective solution in larger magnum handgun calibers. Made in the USA.
It's the powder I have for my .40 pistol loads.
I'm certain otheres will chime in with their preferences too.