I agree with JayC, he summed it up very very well. Let me add that some of these tractors are designed for totally different type of tasks. The
B7510 and the JD2210 are very likely going to be great suburban lot mowing machines for up to maybe 5 acres, yet both of those are still radcially different in stature with the
B7510 offering ground clearance not found on the the 2210 so if a bit of the land is wooded or rough, then the 7510 would have some advantage in those areas of the property while still being very soft of the lawn due to its light weight. On the other end of the weight spectrum is the CK20, it has the most capable front end loader and weighs more than most tractors even larger than its size, it will be slightly better at pulling a small box blade or grader blade due to its weight. Many homeowners use FELs for pretty light duty tasks like moving mulch or similar things, those tasks are easy, even for a light duty FEL. So much of the issue is how the tractor is to be used.
However, I think that really you have 3 tractors (
B7510, JD4010 and CK20) that are reasonably able to be substitued for each other for most every homeowner with typcial chores. If you are mowing, I'd opt for lighter weight due to my clay soil (yours might be different). If you are pulling logs out of the woods, then the heavier tractor would do better. If you are using a Tiller in a garden, using a Post Hole Digger, or using a Snow Blower, then I have found that both light and heavy work equally well.
So are you mowing the lawn or are you loading rock into a pick up truck? Etc?
As for pricing, I suspect the JD4010 would cost a bit more than the JD210. The CK20 and
B7510 are both virtually the same in price (some folks who priced both head to head report one cheaper, other folks report the other to be cheaper) And all pricing seems to be pretty regional so I tend to take it all with a grain of salt.
For your 1.66 acres, I'd be inclined to look at the smaller machines, favoring the JD2210, a Kubota BX, or maybe the
B7510. The smaller machines will get under the trees easier (lower overall height) the seat is less likely to put your eye at the level of the lower branches. The smaller machines will mow better. The smaller machines will turn tighter around your landscaping, fit in between things better, etc.