I have a Lansky, a SharpMaker, and an EdgePro Apex. I never use the Lansky cuz I personnaly found it to be too tedious. I use the SharpMaker on the kitchen knives because it is super fast and works great on my Henckels. I use the EdgePro on my pocket knives to get bragging edges (flat bevels with a mirror finish to 6,000 grit plus hand stropping on CrO loaded paper on glass).
If I had to get rid of all but one, I'd keep the SharpMaker (and a coarse bench stone).
If I had to get rid of all but one, I'd keep the SharpMaker (and a coarse bench stone).