The only best Alternative to Google Adsense that pays just as good would be media.net I've never found any other ad networks to pay as good as Google Adsense.
Media.net is legit just make sure you have the majority of your websites traffic coming from the USA and not from India.
Most people that complain about getting kicked out of media.net and having their money not paid to them are from India and have majority of traffic coming from India.
Media.net wants majority of traffic to come from USA so if your traffic is mostly coming from USA you will get your earnings and keep your media.net account.