The Wall trumps all, imo. It was so unique. The others, while badass, have numerous analogues throughout TV and cinema history. They didn't have the novelty of "Watchers..."
I feel like the Blackwater should be on top. It was the first to do the "it's looking grim but something happens to save everyone last second" thing that happened at the Wall and Bastardbowl. The other battles were basically the same as the Blackwater but better shot due to higher budget. Tyrion vs Stannis is pretty epic too, though I suppose Jon vs Ramsay takes the cake.
It's hard to pic, but I'd say:
1. Battle of the Bastards
2. Blackwater
3. Hardhome
4. Wildling War