I use Ahrefs to check for backlinks and graph to see how website performed over time, in my opinion its the best tool and better than Semrush. Then i check traffic on similarweb which i think is most accurate tool for this, any site below 50K i not look to buy link there. If i am going to spend more money on the link i check carefully keywords and best pages for which website rank again i use Ahrefs, because if its some weird and non relevant keywords, articles that bring huge traffic its possible i avoid the site. So, nobody can tell you exactly what will work for you, you just need to make your own call and if you like some site get a link from there. If you are getting links for free on your amazing content then you can't control things too much. If you are doing outreach again you can check all sites first and then blast your emails.