Guitar Players: Best 4x12 cab for $500 or under
 

I am in the process of buying another cab for my half stack. But I am not sure whehter or not to just get another marshall cab to match the halfstack, or if there is a better alternative out there for not too much more ($500 or less). The Marshall has good bass response and good mids, but the highs lack presence. Idealy I would like to find something that compliments the Marshall. Any ideas?