I actually like seeing ads (though I wish they weren't coming from omniscient ad networks and were instead coming from the sites I was visiting). Content providers get money, I get free content. Nice.

HTML5 Video Ads are what finally switched me to ad blockers.

When people served static images and Adobe Flash videos, I could just disable auto-play of Flash, and voila, I see ads, but don't get obnoxious videos on random tabs. Now I have to block it all to get any peace.

Auto-playing video ads is just bad etiquette.