"億" and "屹" are both very good names, each with its own meaning and characteristics.
The pronunciation of "峄" is "yì", which is the same as "屹", both of which mean soil. When choosing a name, you can choose it based on personal preference and meaning.
The word "屹" means the mountain is tall and straight, symbolizing firmness, stability and tallness. It is a word with power and momentum. If you want your name to have a sense of strength, tallness and stability, you can choose the word "屹".
In general, "億" and "屹" are both good names. Which one is better depends on personal preference and meaning.