I'd probably get the one for smaller diameters (1.5", 2" and 3") as I have a hard time holding down smaller items, and I'd probably cut myself trying to cut around a 1.5" circle. The template would give me more room to put my fingers a bit farther away from the cutting edge. I don't like using anything smaller than my 3.5" square for trimming or cutting.
The other does 4" and 5", and for those sizes and larger, I'd do OK using a plate or pot lid or some other round item out of the kitchen. I use to bake as a hobby, and have cake pans in 5", 6", 7", 8", 9", 10" and 12"
BTW - I switched from baking to quilting due to putting on too much weight - with quilting I don't end up eating my mistakes.