Best tool to check competitor’s backlinks?

Hey guys,
Obviously I want to rank higher than my competitor for specific keywords, so I tried some online tools to check their backlink profile. The thing is, every tool gives me different results, some give me 0 backlinks for a specific site, while others tell me the site has 120000000000 backlinks (yes, that was the exact number…).
So quick question: How do you analyze your competitor's backlink profile?