Where's a good place?
With 5 giants, Stormheim and Broken Spire have the most giants.You can try their challenges hoping to find one with 4 giants or just explore those Kingdoms.
Broken Spire challenge 1, Ogre Tribe, has 4 snotstones team
Stormheim, One Giant Party, second last challenge. For a second choice of battle.
Stormheim and Broken Spire.