In the end, I had to choose Doggy Da Vinci.
A Summer to Remember is...not good, imo. Very boring.
London, We Have a Problem is a great episode; unfortunately, it's not the best imo.
Doggy Da Vinci takes on very serious matters in a respectful manner and shows amazing character development. Plus, who doesn't like Da Vinci?
Other, well I like all the episodes (except AStH as I mentioned and Fear Window), but again none have the best.