self-proclaimed rootbeer connoisseur here lol.  A few worth trying

Bandit's root beer is my current favorite, and their sarsparilla is also good.  Can be found in the cold drinks aisle at Harmons and also for sale at Macey's.

My second favorite is Jackson hole soda company. They sell these at Macey's grocery right now.  They have a Sarsparilla and also one called "bucking root beer", both really excellent. 

Sparky's is one of the better ones out there.  Harder to find but worth it and similar to brigham's brew (honey and vanilla based)

Sioux city sasrparilla is pretty decent

I do enjoy Virgil's.  

If you're local to utah then red rock brewery makes their own root beer and it is really really good. Better than any out of the bottles i listed above.