Based on what I've quickly researched, here is my answer.
I find the European more interesting, since it was the most important and the most decisive. The European theatre includes events such as Dunkirk, blitz, battle of Britain, and D-day. The battles were big, and decisive. The scale of fighting and destruction is overwhelming. The eastern front for itself was most likely the largest/bloodiest campaign ever fought in history between the two armies assembled.
Although, Americans may find the Pacific war more interesting. The U.S. navy and marines were very aggressive and led by excellent commanders. The Navy won some very important victories in the Battle of the Coral Sea.