For me it was the one that let me shadow. At the city where I go to undergrad now, about 95% of the dental offices I went to refused to let me shadow in fear of something (HIPAA, uncomfortable patients, etc.). And it's a big city with one dental office every other block too. The predental club at my university was not as helpful in getting members into shadowing (because they give the opportunities to members with officer positions and seniority, the whole inner circle thing). This was the time when I wanted to see if I really want to go into dentistry so it was very disheartening. I mean, you need to shadow a dentist to be a dentist but if all the dentists don't let you shadow then it just makes no sense how anyone becomes a dentist. Thankfully, this one dentist whose office is about 1h drive away from me agreed to let me shadow because I met him once before through volunteering events. I am eternally grateful for it because it gave me what I wanted, a chance to see if dentistry is the right fit for me. So yea, one of my goals is if I do become a dentist, I will be more than willing to let dentistry-inspired students to shadow me just so that there won't be another kid like me who could've got discouraged going into dentistry.