Since MitsuMan and DesertDevil are not really here, on their behalf : Pajero kicks Nissan **** anyday, anywhere, anyhow!
But seriously, if ruggedness is the only factor, then its not really a discussion here. But as Sherwan rightly links ruggedness/reliability with good maintenance, parts availability and maintenance cost also becomes relevant. But since your talking about old cars here, in the end whats perhaps more important is the current state of any particular vehicle rather than what its pedigree is.