I like any flower as long as it is blooming, but if I had to pick an absolute favorite, daffodils would be right up near the top of my favorites list -- tied with all my other "best" favorites.
Seriously, daffodils are one of my favorite flowers. They are easy to plant and care for, bloom big and bloom early, and nothing says "Happy Spring!" quite like the daffodils.
In my Pennsylvania garden, we planted thousands of daffodil bulbs and left them in place to seed about and naturalize along the edge of the oak woods. Over the years they really did increase and the effect became a true "sight to be seen." Those daffodils are one of the things I miss the most since moving to California.
Many types of daffodils will last for years and years in your garden with a minimum of care, especially if you plant varieties that are said to "naturalize well". Whether you are trying to naturalize a planting area with daffodils or grow them in your flower bed, the most important thing you can do for them is leave their foliage in place until it turns brown and dries up.
This is a natural process that rebuilds the bulb's strength so it can bloom again next year. If you remove the foliage too early, the bulb will be weakened and will eventually fail to bloom at all; if you promptly mow them off short every year, soon they will disappear. (Another common cause for failure to bloom is that their planting site has become too shady as neighboring trees grew up over time. Or they may have become overcrowded. Or they might need a little fertilizer. But that's another story.)
Those daffodil leaves keep growing, elongate and eventually flop over and then it takes weeks and weeks for them to finally die back. This progression can look "unsightly" in the garden, but it is a necessary process. I think the flowers are worth it. Think of it as paying back -- or maybe paying it forward!
You may hear or read suggestions for braiding the daffodil leaves or bundling them up with rubber bands and who knows what else, but it doesn't help the bulbs at all to do this and it is a lot of extra work for the gardener, too. Eventually I will write out some sneaky (easy) suggestions for hiding the foliage while it grows and dies back, but in the meantime, give yourself -- and your daffodils -- a break:
"Leave the leaves alone!"
ps It is okay to deadhead your daffodils, meaning remove the faded blooms. Deadheading helps conserve the bulb's energy by preventing it from setting seed. This helps develop bigger, stronger bulbs.
On the other hand, if you are trying for a naturalized planting of daffodils you may WANT them to seed about. In that case you would leave the blooms on the plant to encourage seeding.