Best Rosemary for Topiaries?

I am interested in making a Christmas tree topiary and traditional round tree like topiary. What varieties of rosemary do you suggest?

I would suggest an upright variety. If you pick one with pretty flowers the topiary will look decorated all by itself during the summer flowering season. You could try Arp, Benenden Blue, Blue Boy, Golden Rain, Pine (lovely for this use!), Pink, or Rex.