Xfinity (Comcast) is the default home-internet choice in Boulder for a simple reason: it reaches almost everyone. Cable runs to roughly 92% of Boulder addresses — more than any other wired provider — so for a large share of the city, the real question isn't whether Xfinity is available, it's whether it's the right buy …

Quantum Fiber is Lumen's fiber-to-the-home brand — the same company behind CenturyLink, but pointed at the future instead of the copper past. In Boulder it's the only widely sold connection that delivers symmetrical speed, where your upload matches your download. The catch is availability: fiber reaches only about 40% …