Calgary has a very competitive Vietnamese restaurant market. Chi Lan is a reliable and affordable bet. It offers great value and decent vermicelli. They do a few things differently than the standard norm, such as shredded cabbage adding some nice colour to the Bun vermicelli. Prices are very reasonable, with each Bun option being under $10.
Service is good, and the restaurant itself is very clean, modern, and well laid out. It's a safe bet!