JL easily wins. The fight would go Batman vs Captain America; Wonder Woman vs Thor; and Superman vs Hulk
Batman vs Captain America- Batman wins because he is smarter, faster, and a more skilled/wiser fighter. Plus, he's better equipped and his strikes are so powerful that he once winded the Hulk in a crossover comic.
Wonder Woman vs Thor- this would definitely be the closest fight,but Wonder Woman wins. They are almost identical in strength and durability, but Wonder Woman is a more skilled fighter and she is a lot faster than Thor. Not to mention that she is better equipped with all of her godly weapons and her lasso.
Superman vs Hulk- Superman wins with very minimal struggle. He is much stronger, faster,more durable, more skilled, more experienced, and he has a better variety of powers (heat vision, freeze breath). After Superman finishes Hulk off, he can help Wonder Woman beat Thor