Since you already have a Lansky, get a Lansky course and meduim diamond stone if you don't already them -- use these to reprofile a blade or deal with an extremely dull one.
Get the Sharpmaker to maintain your blades. The Sharpmaker is superb at maintaining an edge and a lot faster and easier to use than the Lansky; but, unless your blade profiles match the Sharpmaker's 20 degree angle or less, it will take you quite a long time to remove enough metal to get to the edge with the Sharpmaker. Diamond rods for the Sharpmaker work pretty well; but, they will cost you more than twice what two diamond stones for the Lansky would set you back.