In my opinion, a good vet is one who takes time to get to know your puppy, handles him gently, tries to ensure as best he can that his experience with be a positive one.
If your vet handles your puppy roughly, seems impatient, doesn't try to make any type of connection with your puppy, you may want to rethink your choice.
It's not unusual to visit a number of clinics and veterinarians before making a decision. It's also not unusual to change your mind.
When I began feeding my dogs a raw diet, I had to change veterinarians as the one I was using did not support my choice to do so.
At a recent visit to my current vet, we were discussing the importance of making a connection.
His comment was - I have a very short time to make a good impression so I use liver treats!
That's what I want to hear :)
Sadly, there are veterinarians who do not take time to make any type of connection. Not long ago I was discussing puppy care with a client.
She proceeded to tell me her vet did not believe in using any kind of treats and didn't seem to make any effort at all to relate to the puppy. Not even an ear scritch. It was all business - in and out fast.
Puppies in their first 3 months are very impressionable. One bad experience can be strong enough to have a lifetime effect.
There has been much research done documenting the effectiveness of using treats to teach puppies that scary things don't have to be scary. The American Veterinary Society of Animal Behavior has a Position Statement on the importance of early socialization and having positive experiences.
The simple act of giving a puppy a few liver treats while in the clinic can go a long way in making it a less scary place to be. One of the things I recommend to new puppy clients is to visit their vet clinic a few times with the sole purpose of having the puppy spend a few minutes in the clinic, up on a table getting treats and belly rubs. I want their early experiences to be good ones.

Hearing about the lack of any attempt at making my client’s puppy comfortable was disturbing.
There was other information that came out which was unacceptable to me and I felt compelled to tell my client I strongly believed it was in the best interest of her and her new puppy to seek out a new veterinarian.

Your new puppy will spend a lifetime visiting the veterinarian's office for one reason or another: vaccinations, ear infections, heartworm testing, yearly check ups, not to mention emergencies.
I would hope one of the reasons behind the profession is a love of animals along with making a living. I think for the most part that's true.
I want to know my vet understands my puppy may be scared and uncomfortable and will take a few moments before beginning any procedure, whether it's liver treats, an ear scritch or getting down on the floor to play.  No matter how busy my vet clinic is, they always have time for a cookie and a smile. 
                 
There are a few things to consider when choosing a veterinarian clinic : cleanliness, attentiveness of reception, services offered, are the hours convenient, how many Doctors are there, emergency protocols and the most important of all - how does the vet relate to your puppy? Does he/she interact with the puppy? Play with the puppy?
Most of us find clinics via referrals from friends or relatives. That alone should not be the reason you choose a particular veterinarian. We all relate to people differently.
Bottom line: your gut is often the best indicator.