I really like 3 for pistol,
Something on the faster side, Titegroup, HP38, AA#2
Something in the middle WSF, Silhouette
and H110 for full power .357.
If I had to settle for one to do everything pistol wise
, maybe N330, N340 or HP38/W231.. (I like the VV powders, but they are more expensive and sometimes hard to find, but if I can have only one....)
BE86,Unique,Universal, Powerpistol (anything midrange pistol burn speed)might also be good choices for only one.
25 VihtaVuori N320
26 Accurate Arms No. 2
27 Ramshot Zip
28 Hodgdon HP-38
29 Winchester 231
31 Alliant Unique
32 Hodgdon UNIVERSAL
33 IMR, Co IMR UNEQUAL
34 Alliant Power Pistol
35 VihtaVuori N330
36 Alliant Herco
37 Winchester WSF
38 VihtaVuori N340
40 Ramshot True Blue
41 Accurate Arms No. 5
42 Hodgdon HS-6
43 Winchester AutoComp
44 Hodgdon CFE Pistol
45 Ramshot Silhouette
(listed by burn speed faster to slower)
anything above would probably work for only one if you had to have only one, faster ones will make the .45 happier, slower ones will make the .357 happier.....
HP38/W231 won't get me top vels but it works in about everything (pistol)decent to excellent and it's my .45s favorite, of course most of my 9mms would argue for WSF, (but all of them won't agree on a favorite)
WSF does not have a lot of listed data but with care loads can be worked up for it in things that no data is listed for.