Different tools. The Aligner is much better for reprofiling but slower for touch-ups. I don't personally have experience with the Sharpmaker but I read very good things about the edge it produces, especially with the extra-fine stones. It's probably the best system for touching up healthy edges. The golden mean would be to buy one for setting bevels & the other for touch-ups. You could set the bevel real thin with the Aligner & touch up at 20 degrees with a few licks on the Sharpmaker.
I've had the Aligner for many years & get great results. I've bought the XX course stone for removing massive amounts of steel & the XX fine stone to finish on, neither of which are included in the regular kit. The stones work fast, stay flat, & last extremely long unless you use too much pressure & strip the diamonds. Once you get the hang of using the system you can get extremely fine edges, especially after some feather-light passes on the pink XX fine (8000 grit) stone. You can micro-bevel a bit by giving the knob a quarter-turn or so for the last few passes too. I'm no sharpening whiz but I can always whittle hair if I take my time finishing the edge on the 8000 stone.