First off, you have to eat good pho to know what good pho is and even if you think you had you good pho, you will be back to the same joint as nothing compares to it.
I'm an adventurer seeker so I don't have a fan favorite so I can't tell you what or how or where the good pho is at. If it is up to me, I compare all pho to how the pho I grew up with which is home made pho from my elders.
In general, I think the good pho are usually near the viet community. They are marketing it to the viet people so you better make your pho good cuz you can't fake the funk with the viet people and their viet food. They can make or break your business.
Then again, taste is also subjective so if you are satisfied with paying x amount of money for a satisfying bowl of pho then that is all that matters. Don't let the viet person sway you away from better pho or you will either be telling yourself " where I've been all my life to miss this" or "you ruin me completely as I am better not knowing"