Considering the looming threats of dany, faegon, euron and the white walkers, who on the iron throne could prepare the realm for all this?
Stannis, he won’t be popular, but he’ll be effective.
Stannis is the most straightforward choice, but remember that we still don’t really know what the Others are or how they can be defeated. If the only thing that can defeat them is fire, then the the best WOT5K outcome might be whoever leaves the realm most vulnerable to Dany’s invasion so that she’s in charge and invested in the fate of Westeros when the Others arrive, which probably means Joffrey. If the only thing that can defeat them is Bran and/or the COTF, the ideal victor is whoever is most likely to take Bran and ice magic most seriously, which might be Robb, given the family connection, belief in the Old Gods and the likelihood that Robb himself was a warg.