This is 3 different channel knives, from left to right:
Zyliss, Victorinox, and Messermeister. In terms of ease of use, from easiest to more difficult: Victorinox, Zyliss, then Messermeister. In terms of flavor, from most sweet to bitter: Messermeister, Zyliss, then Victorinox.
If I had to make a large amount of bitter marmalade, Victorinox FTW. For a nice balanced Seville orange marmalade, Zyliss!