This has been answer many times but my list of criteria is:
1. High Relevance to your web site
2. High mozTrust (SEO - Search Engine Optimization | Tools & Software to Rank Better)
3. High mozRank (SEO - Search Engine Optimization | Tools & Software to Rank Better)
4. High Linkabilty
5. High Traffic (Alexa the Web Information Company)
6. Domain Name Age (the older the better)