I do believe if you can think of an iterative solution, it's always better than using a recursive one. And technical y every recursive solution can be converted into a equivalent iterative one.

```
public int maxDepth(TreeNode root) {
if (root == null)
return 0;
Deque<TreeNode> stack = new LinkedList<TreeNode>();
stack.push(root);
int count = 0;
while (!stack.isEmpty()) {
int size = stack.size();
while (size-- > 0) {
TreeNode cur = stack.pop();
if (cur.left != null)
stack.addLast(cur.left);
if (cur.right != null)
stack.addLast(cur.right);
}
count++;
}
return count;
}
```