The powders that are considered "Magnum Powders" are: AA#9, Alliant 2400, W296/H110, both IMR & H4227, Ramshot Enforcer and VV N350. You can add Hodgdon Lil'Gun for heavier bullet in the .357 Magnum. (158gr and heavier)
All will do a very good job so pick the one that's made by the company you like best, look up the proper charges and load up some ammo. Note, those are all the powders that are used for full power Magnum rounds. You can use slightly faster powders for less velocity and downloaded rounds too. (like HS-6, Longshot, Unique, True Blue, AA#5 and others in that burn rate range)