If heavy road use is the main priority, then the independent every time, it handles and rides better as it was Daihatsu's attempt to keep up with other more road orientated vehicles. This was achieved without ruining the off road ability, which was slightly worse than the leaf srpung model. The differences off road were not noticeable to the extent that a slightly differing driving style meant they were equal.

Considering your stipulated requirements, the indy would be a much better bet, they were slightly better in snow and in less arduous terrain. Several things to watch for though, the spring mountings can corrode if heavily used as many were, and the ends of the coils would snap if heavily loaded or subjected to continuous heavy towing. Both easily checked for with a visual inspection with a torch. Check the ride height of the vehicle as many have been fitted with uprated springs from aftermarket suppliers, these were generally uprated by 20 percent, great for heavy towing, but reduces reduces unladen ride quality.
Indy's were fitted with updated engines, this was to reduce emissions, they had about 2 BHP less, and the bottom end was not quite as strong, requiring slightly more engine revs over the earlier models. A check of the injection pump is required by driving to ensure the turbo kicks in at the correct engine revs, as it needs this at the bottom end. Avoid smokey ones which could indicate a turbo on its way out.

Being fitted with coils reduced the bouncy ride of the unladen leaf sprung model, the considerable suspension noise, and the continuous squeaking of the suspension bushes.

All in all a much better model for your requirements.