Best is a hard one to answer. They all have purpose!
Spring is beautiful because we watch the new life thrive. Mating is in the air and the breeze carries its warm joy across the land.
Summer is fruitful as the thriving new life joins maturity and we bask in the warmth of the sun rays with no worries in the world.
Fall allows us to appreciate life as we watch the greenscape turn a vibrant plethora of colors as we take on last breath of its beauty
Winter however serves a greater purpose. Winter brings hope. Because as we stare at the white wasteland of a leafless frozen forest we can appreciate how short the life cycles are and look forward to the new thriving life in the spring.
Definitely winter!