Since every person is unique in their combination of visual needs, ocular health, and amount and type of prescription it's hard to say that one type of lens is absolutely the best for everybody. But now that we have that disclaimer out of the way, I would say that 'dailies," or lenses that are discarded on a daily basis, provide a unique combination of benefits that 2 week and monthly lenses simply cannot offer.
The first unique benefit of dailies is convenience. In fact, dailies are the MOST convenient type of lens on the planet. It's the lens that doesn't need to be cleaned. A person simply wakes up, opens a new lens, wears it for the day, throws it away at the end of the day, and repeat the process the next day. There's no need for cleaning solutions or lens storage cases. Also, you don't have to keep tabs on the replacement cycle on your calendar as with 2 week and monthly lenses.
The second unique benefit is better ocular health by reducing the risks for eye infections. Quite simply, a lens that is discarded every day doesn't give bacteria, viruses, or fungi a chance to reproduce and cause ocular complications as with 2 week and monthly replacement lenses. While patients love the convenience of dailies, optometrists love the safety.
Another unique benefit of dailies is improved comfort by way of reduced lens deposits. Throwing a way lens every day prevents the buildup of oils and proteins which can decrease lens comfort. Also, there is less buildup of allergens (pollen, dust, etc) so there is less chance for allergic reactions in the eye when compared to 2 week and monthly replacement lenses.
So while every person's contact lens needs are unique, dailies do provide an improved wearing experience for a large number of people.