A bike's quality isn't related to its number of gears. Single speed versus geared bikes fill different needs.
On a 100 mile road race, you'll find everyone is using geared road bikes, because that's the best tool for that job.
A NYC messenger is often riding a single speed, because that's a pretty good tool for that job. Nimble, no fuss, light weight, minimal.
In a velodrome track you'll see single speed bikes with steep gearing, but you won't see hills, and the whole race is over pretty quickly. Gear changes would slow them down.
A single speed can be used in hilly terrain, but it's often not considered as well suited for extended climbs and descents. A geared bike is preferable in those circumstances. But if you're bringing your bike on a subway, and spending your time weaving between cars and track-standing at traffic lights, a single speed is probably ideal.
You haven't said how you intend to ride; to what purpose you are putting this trusty steed.