When you say "best shingles to buy", does this mean you just want to buy them and do it yourself? If that's the case the big box stores have good deals on reputable brands like GAF and Owens Corning. If you are using a contractor, most will have figured out what to use over the years and what gets the fewest warranty claims and will recommend accordingly, just have an idea of whom you are dealing with. But aside from the 2 mentioned, Tamko and Certainteed are good solid brands. Keep in mind warranty issues, for example, Certainteed will offer a longer warranty if their product is used for all aspects of the install (shingles, felt, ice/water shield and ridge vents).