Do you understand that the larger the cog (greater number of teeth) the easier it is to pedal and to climb with. The smaller cogs let you go faster but require more effort. An 11x32 will let you climb more easily in the 32T cog then an 11x28 will in the 28T cog but will be just as potentially fast since they both have 11T smallest cogs. A 12x25 won't let you climb as easily or go as "fast" but it will have closer spacing and less of a gap between the gears. That said, very few riders can make effective use of an 11T cog on anything but downhills so not having it is not a handicap for the majority.