I would lean towards the QF III just because of the weight consideration. You would still need a 4 wheeler or snowmobile to pull it any distance and need two people to load and unload it. The QF III is also shorter when packed that the other two by 3.5" on the Grand Caravan & 5" on the Triplex. Also the bench seat makes seating more flexible than the Triplex, not sure if you would get 4 people in it though. I have several products from Eskimo and they have all held up well and their customer support is very good. It all comes down to personal preference, go to farm & fleet or fleet farm they should have all 3 on display. Walmart also usually has the eskimos, not sure if they have the III or QC, I know they have the QF II.
If weight is not a considerartion I would go with the Grand Caravan for size and seating flexability.