44 Mag is the most useful to me. It, and 44 Special can be load to fit into a lot of different loads. Small, medium, and large game, self defense, bear defense, target shooting, ect. It's an extremely versatile round.
Out of a rifle, it can really do some damage to whatever it hits. One of my favorite hot loads is a hefty load of H110 behind a 200gr bullet. Out of my 20" barrel, I'm getting just over 2000 FPS. It kicks hard and hits like Thor's hammer.