Lacking details of the Felco sharpener specifically, any diamond hone in the 320 - 600 grit range generally works OK for the uses you describe (garden tools, kitchen knives, utility blades, etc). If choosing an alternate brand, I'd bias my choice more toward the 600-grit end of that range. The tools to be sharpened by such a hone are usually in soft(ish) steel with little wear-resistance; so, anything very coarse in a diamond grit will eat it up fast and leave a pretty rough edge. A 600-grit diamond hone, used with a light touch, would handle such work easily for touch-up maintenance.
For garden tools & such, I actually prefer using a mill bastard file for resetting edges completely; that works very well. But the diamond hone can work in follow-up maintenance, with a light touch and minimal passes.
A lot of general-use consumer diamond hones on the market often default to around the ~ 600-grit spec, which would compare to something like DMT's 'Fine' hones (though DMT is more uniformly-graded, leaving generally cleaner edges than most of the less expensive, similarly-rated options).
