NASA, Russia, and ESA have between them already sent probes to most or all major planets and many of their moons and several asteroids and comets. When interstellar probes are sent, thney will also go in all directions. It's not a question of picking just one.
I understand that. My point remained, before chimera's response, that if you have 1,000,000,000 probes and 1,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000+ possible destinations, some choices will have to be made, and for a valid reason other than what the heck.