To try to help with the confusion, what you really need to do is consider that different tractors are made for different purposes. Now each tractor is a compromise for most people simply because most people buy ONE tractor for MANY jobs. So you need to balance the types of jobs and find the best tractor for the HIGHEST PRIORITY jobs you are going to do.
For example here is a list of typical jobs for a SMALL (20 to 25hp) tractor:
Mow the lawn -light
Dig post holes -neutral
Bushhog small fields -mid-to-heavy
Move mulch -neutral
Move dirt -mid-to-heavy
Spread fertilizer -neutral
Pull modest logs through the woods -mid-to-heavy
Till a garden -light
Snowblower -neutral
Snow w/FEL -neutral
Box Blade work -mid-to-heavy
Your best thing to do is look at the jobs YOU want to do and then try to figure out how many HOURS PER YEAR you will do those jobs. Then buy the best compomise tractor that is most suitable for the jobs you are going to do.
For example, mowing the lawn, tilling the garden are both PTO intensive jobs so you want a tractor that has plenty of PTO horsepower. Both are also jobs better suited to lightweight machines because they cause less soil compaction. Now if box blading and log skidding are high priorities, then the adage 'weight = traction' would lead you to a heavy tractor. Jobs like operating a PHD are neutral, most any tractor will run a PHD.
Figure that the average tractor owner/homeowner puts between 50 & 100 hours a year on their machine. If you are planning on using it for mowing, then mowing & light yard work is often 50% of the hours. That alone can explain why Kubota's marketshare has recently exceeded 50% in most of the country and is at 60% in some areas.
Now if you are not mowing, then you are very likely using a box blade, moving heavy materials, dragging things around the woods, and probably doing some hogging. Those are going to be tasks that are easier to accomplish with a heavier tractor, they will favor weight. Mahindra has grown to the #4 tractor company in the US because they have some nice machines that do those jobs very well.
As for a light tractor being a light duty, that is probably partially true, but in the homeowner market, that is not a sign of lack of quality. It takes greater metalurgical skill and often higher grade raw materials to make strong light weight castings than it does to cast heavy ones. Not to say that a heavy tractor is lower quality, I do not want to imply that in any way. But heavy and light are not necessarily indicitive of either quality or duty, more they are a difference in philosophy of building.
Since you do not indicate WHAT your jobs are or intended use of the tractor, it would be hard to advise you as to what would work best.
