Petco is my favorite park. Thoughtfully designed with a lot of little hooks, like the deck chairs just pass the left-center wall, the berm past there, view into the city, the integration into the neighborhood with all the walkable restaurants/bars. You'll notice a lot fewer Padre fans heading out in the 7th and 8th compared to Dodgers/Angels whose stadiums are surrounded by fields of parking lots.
Oracle is a close second, but Petco has better weather for night games.
I agree with comments about Leeches Stadium in Baltimore. Among many issues, the surrounding neighborhood is one of the worst in the league.