You can pick pretty much any handgun or shotgun powder to start. As mentioned, the key is to have enough volume taken up to reduce the odds of double charging. That is the appeal of Trail Boss. For similar applications I've used;
Alliant: Red Dot, Green Dot, Unique, Herco, American Select, Bullseye, Titegroup. BE-86 would probably be another good one to try though I haven't at this time.
Hodgdon (and others under their umbrella): Clays, Universal, International, HP-38/Win 231, Solo 1000, Nitro 100, 700x, H4227, Accurate No 5, True Blue.
Some powders were a bit more consistent than others but they all worked well enough. My favorites of these are Titegroup, Red Dot, Unique, 700x, Clays, Universal, No 5, HP-38/231, and Bullseye. They seemed to be the least sensitive to powder position in the case.
There are newer powders that should also work but I can't speak for them yet. Some examples would be Win 244, CFE Pistol, and Competition come to mind offhand. I've used Competition in the 45 ACP but not in larger cases. There are discontinued powders like SR 4756 and 7625 that were well liked at one time and can still be found on occasion.
Bullet weight seems to be a more important factor in regulating a load to the sights than powder charge. Most of my experience with fixed sights have been with 38 Special, 38 S&W, and 45 Colt and I found 158, 200, and 250 gr bullets to be pretty easy to regulate a load. Deviate from these weights and things quickly became problematic.
