Best Adsense Alternative?

Needing some opinions on the best advertising alternatives to Adsense that are available. Any input is appreciated.

Long story short, I opened up an account with them, placed the code on my site, was earning a decent amount of money, and was then notified that my account had been closed. I tried to appeal it, but had no luck. The notification didn't even give any reason as to why the account was closed.

So now I'm looking at what other options are available. Kind of ridiculous that I have to do this, but it's my only choice. Either that or direct advertising.