If you want the longest service life with the least maintenance, here's my opinion (up for disagreement / contention by others):

Points to ponder:

- nearly any bike will give you a good service life at 4,000 miles per year, if properly maintained
- Quality does make a difference. $1500 is a reasonable price point to get something that will offer many years of reliable service.
- Disc brakes eliminate rim wear due to conventional brake pads, and tend to be easier to maintain than rim brakes. They also offer better braking performance in wet conditions. Cable actuated disc brakes are the simplest format, and are easy to set up and maintain. Hydraulic systems tend to offer better performance/modulation, but are not as simple mechanically. In theory, hydraulic brake systems are neary maintenance free but are more involved to work on should something other than new pads be required.
- Internally geared hubs (IGH) can provide many years of trouble-free service with a very modest service interval. IGH's replace the conventional drive train (derailleurs, cassettes, multiple chain rings, narrow chains) and are far easier to keep running smoothly over time. There's a slight but inconsequential learning curve with rear wheel removal when compared to conventional systems.
- For conventional drive trains, Campagnolo components are fully rebuildable while Shimano components generally are not. I don't know about SRAM. Most bikes have derailleurs, and with proper care can run smoothly and reliably for many years. For decent quality systems, maintenance tends to be higher in time and cost than wih IGH systems.
- bearing races will wear over time, but if properly maintained will give many thousands of miles of service.
- Tires will wear out with use. Good quality tires cost $30-70 per tire and tend to offer superior ride quality and/or puncture protection over less expensive models.

A single speed bicycle is the simplest, most reliable, easiest to maintain type of bike that you will find. If you live in a hilly area or will be riding with large loads (or are not in good physical condition), a single speed may not be the best choice.

My own personal choice for utility, reliability, service life, ease of maintenance and pleasure/simplicity of would be:
- Internally geared hub
- Disc brakes.
- dynamo driven (no battery) lighting system
- any frame material (though I prefer chromoly)
- good quality components
- good tires