As someone who's been a lab tech AND a teacher, let me tell you what kind of experience you'll get:
Lab tech: Test tubes, learning repetitive lab procedures, interacting with a small number of people who are either obsessed with what they're doing or can't wait to get to their next adventure, presenting a relatively small variety of data to a relatively small group of people
Teacher: Paperwork, interacting with over 100 people everyday - no 2 are alike, learning how to get all of them organized, processing a large amount of information in a short period of time, tailoring practices to the individual needs of each of your students, being a member of a team of professionals (counselors, administrators, custodians, parents, other teachers) to find the best practices for your students, constantly making split second decisions, presenting a wide variety of data to a wide variety of people....
This list doesn't even touch on the medical, social, and mental issues you have to deal with on a regular basis.
Need I go on? You decide which one will give you better experience in being a doctor.
BTW, the root of the word "doctor" is...you guessed it - "teacher"
One more thing - I truly think being a doctor will be an easier job than being a teacher (although that's not why I'm switching careers).