Which domain is better for SEO?

Second domain is the best for SEO.
There are many web sites that can help you search for available domain names based a keyword and a theme or topic that you pick. For example, if you were building a web site for a cleaning business, you might try keywords such as "cleaners" or "cleaning", and choose a theme based on key attributes of the business, such as fast service or it being an environmentally friendly cleaning company. You might need to try a few searches, but stick with it, and it shouldn't be long before you find some good possibilities.