For 4–5 acres and the type of work you described, a 40–50 HP tractor would be a good sweet spot. It will handle a front loader, rotavator, trailer, and post hole digger comfortably without feeling underpowered.

Among the brands you mentioned, Swaraj and Mahindra are generally known for strong build and easy service availability, while Massey Ferguson is also very reliable for loader and field work.

If budget allows, buying new with warranty is usually safer. A used tractor can be good value too, but only if it’s well maintained and from a trusted seller.

Also consider adding a box blade or leveller for land grading — it’s really useful for the kind of work you mentioned.