Rifle loading requires more flexibility in reloading steps than does pistol reloading. Different dies, powders, bullets, seating depths, etc. are often used in rifle reloading. Progressive pistol reloading is often more about cranking out mind-numbing quantities of exactly the same load with minimal effort.
The Dillon 550 is better suited than the 650 to rifle reloading for reasons already addressed, but the LNL AP is better suited than both.
The LNL AP has a PM that is better suited to rifle powders than the Dillon PM. Pre-set metering inserts can be changed with the push of a button, without having to empty the PM. And if/when you need to change powders, the LNL PM drain allows you do do that without tools and without having to remove the PM from the press.
The LNL PM can be used at stations other than the 2nd station, unlike Dillon 550/650. This allows more than one die prior to loading powder. You could have a neck size and a shoulder bump die, and/or a case lube die, separate expander die, etc. The extra station on the LNL may come in handy here.
Removing/replacing individual dies and tools is much easier on the LNL AP; a simple 1/6th turn and the die pops out. This also allows auto-indexed single stage reloading (even with the case feeder), since all you have to do is remove the dies/tools that you do not want to use for that operation. The press automatically moves the brass from the case feeder (if you have one), through the station you are using, and into a bin for you. And if you need to manually remove or replace a cartridge, you don't have to fumble with little brass buttons, just pull the little coil spring down and remove/insert the case.
Like the 550, the LNL AP primer feed only dispenses a new primer when needed. The 650 dispenses one for every pull of the handle, so it cannot be used for turret style reloading (one cartridge, start to complete, at a time on the press) like the 550 and LNL can.
If money is no object, and you shoot a lot of military brass with crimped primers, the Dillon 1050 is great, with primer pocket swaging built in, but at a price that would pay for 2-3 really nice 650 or LNL AP presses with all the trimmings.
Andy