For reloading rifle cartridges, the LNL AP offers a lot of flexibility not available in Dillon 550/650. The AP powder measure works better with extruded rifle powders than the Dillon PM. The AP PM works in any station, but the Dillon PM only works in station 2. Individually removable dies make it easier to swap out a FL with a neck sizing die, or include a shoulder bump die along with a neck sizing die, add a lube die, etc.
If you reload a lot of military brass, the Dillon 1050 has on-the-press primer pocket swaging. You can swap out the Dillon PM for a Hornady/RCBS PM and case-activated linkage too.
Andy