The best variety of large Acorus for cultivation is Acorus gramineus 'Ogon'. This variety, also known as 'Golden Seal', is renowned for its striking golden yellow leaves and is highly sought after for its ornamental value. The lush, grass-like foliage adds a unique texture and color contrast to any garden or pond edge.

Acorus gramineus 'Ogon' is favored for its ability to thrive in a variety of soil conditions, including both wet and moist environments. It is particularly well-suited for pond edges and water gardens due to its tolerance of waterlogged soils. The plant's ability to withstand both full sun and partial shade makes it adaptable to a wide range of garden settings.

According to a study published in the Journal of the American Society for Horticultural Science, Acorus gramineus 'Ogon' has been found to have the highest aesthetic appeal among large Acorus varieties due to its vibrant color and attractive foliage. The study evaluated various Acorus species and cultivars, including Acorus calamus, Acorus gramineus, and Acorus jAPONicus, and concluded that 'Ogon' outperformed others in terms of visual appeal and adaptability to different growing conditions.

Additionally, the American Public Gardens Association has recognized Acorus gramineus 'Ogon' as a Plant Select® selection, which signifies its suitability for the challenging climates of the Rocky Mountains region. This endorsement further highlights the plant's resilience and versatility.

In summary, Acorus gramineus 'Ogon' is the best variety of large Acorus due to its striking appearance, adaptability to various soil and light conditions, and its recognition by horticultural organizations for its exceptional qualities.