Unless you plan on driving the rated mileage of a tire within about 2 years, then don't be too concerened about the rated tire mileage. While the thread may go that far, the tire itself will not be performing anywhere near it's original capacity after about 2 years depending on how they are used. The tires will really harden and begin to get brittle. Traction will suffer greatly when this occurs. You may say you don't drive hard enough to need the traction, but consider that it only takes one occurance of not being able to stop in time for an accident to occur. You're collision deductible will probably be higher than the difference in cost of the tires you are considering...
Even then, generally speaking, cheaper tires tend to have cheaper rubber and may suffer from heat cycling much sooner.
The best way to choose a tire is to decide what type of tire you need (high performance, all-season, winter, etc), determine which are available in the size you need and get the best one you can afford. Not necessarily the most expensive, but in a general sense, you get what you pay for. The higher priced brands tend to have tires that operate better for longer periods, are quieter and have better low tread wet traction. Most tire tests rate their perfomance when new, so little, if any insight will be given about their long term performance.