No offense intended, but this is almost like asking what gun is best? I mean, what is the intended use?

If someone just needs something for car camping in moderate temps, they would be fine probably with anything from Wal-mart or someplace. If they need something for extended winter camping, they'll want something else.

You probably know that high fill down (e.g. 850)is generally warmest and most compressible, but becomes nearly useless when wet. The synthetics don't compact as well but still insulate when wet.

There's also the size to consider. "Normal" size people can use most bag, but big folks need to get bags that are cut larger.