I like them both, and wouldn't want to be without either. You asked though, specifically about which is best in .44 magnum.

I own quite a few ,44 magnums and have owned a boatload more. I also own a darn good chronograph that I have had since about 1988, and I had a cheaper one before that. In my experience with all of the .44's that I have owned and chronoe'd, 2400 has always given higher velocity with recommended top end loads than H-110/296 with bullets that weight up to 240 grains. With 300 grainer's and up, H-110/296 provides the highest velocities.

At first that was a hard pill for me to swallow, since I had burned up hundreds of pounds of H-110/296 to get what the books were all saying was the top velocity obtainable, before finally trying 2400 in the late '80s.

I like the fact that 2400 doesn't require a magnum primer to burn completely ( Alliant doesn't recomend them for it either), and I haven't experienced any noticable variation in load uniformity/SD's or anything else with standard primers, though I know some have found magnum primers work best for them. I won't argue with their results, since all guns are different. It takes a couple less grains of 2400 to do the same thing as H-110, but it'd take quite a few rounds downrange to see the savings.

Either powder drops easily, and accurately from my old Pacific powder measure.

There's a touch of nostalgia, and a connection to history when using 2400 in a .44 magnum that appeals to me too.

In the end, you can't go wrong with either in the .357, .41, .44, .45 Colt, and a few others too like the .45 AR, and .38/44 HV rounds.