It's important for sb

It is important for sb to do sth

I choose the first one.

1. sth be important to sb.（自己的想法）是指你对这件事很关心，很在意，想的很多。

e.g. Nothing could be more important to me than my family.

2. sth be important for sb. （外人的看法）某事对某人非常重要

e.g. It was important for the president to continue his schedule, regardless of the bomb threat.

Hope it helps!

这2句话都没有错.主要是看你用在什么情况下了.
用法不同