For purely technical reasons the pen is better as it scans better, clearer. For artistic purposes the pencil is mightier than the pen...to borrow a phrase. It depends on what you're shooting for, though...if you're wanting to keep the hand-drawn look then go pencil, if you're looking to do a lot of post work on the computer then use the pen. In terms of aesthetics, the water on the north seems to blend better while that on the east seems to be more like rings. Try using some colored chalk then rub it/blend it with your fingers for a smoother transition or get some really soft lead colored pencils. I haven't used smudge sticks so maybe they can be blended in a similar way.