What is the best tai chi style for people over 50?

The slow motion, short form styles are generally best for people over age 50 because they generally take longer to learn movements than younger people. The Chen style is not recommended for older people, because of its stamping, jumping, and sudden moves. The small frame styles (Wu and Hao) generally have higher stances than the large frame styles (most Yang styles). For older people with weak or injured lower backs or knees, forms with higher, rather than lower stances are better. The small frame styles are usually better for upgrading the health of your internal organs.