Cointraffic and coinzilla are the most used crypto ad network by publishers or site owners running ads on their sites. Although this two have strict rules when accepting sites on their list, your site should have enough traffic well at least 30,000-50,000 visits per month, i'm not sure the numbers but higher is much better especially on coinzilla. Cointraffic minimum withdrawals is €25 for bitcoin, and €200 or 300 for bank transfer/wire, i just not so sure on coinzilla since my site never accepted there unlike cointraffic.