I have a Chromecast and I love it. You get what you pay for. I think Apple TV costs around $99 right?
I got my Chromecast at $35 and it does everything I need it to. It streams Netflix, Hulu and movies I torrent download all onto my TV screen. Occasionally when I stream from a web browser there is a lag in sound ( probably 1 % of the time)
I think someone said it in here, one annoying feature is that Netflix doesn't autoload the next episode, BUT Hulu does, so take the good with the bad I suppose?
I'm not too familiar with the setup/ takedown of Apple TV but the thing I like about my Chromecast is I can easily unplug it from my living room TV and bring it into my bedroom and simply plug it into the TV, very easy for traveling. I have often brought it over to my friends or parents house, it travels really really well.
The one thing that bothers me and I completely understand it, is that you can't play ITunes shows or movies on it. I get it, its competition.
If I had the $100 dollars and I had the choice between Apple TV and Chromecast, I'd probably go with Chromecast again, due to superb playback quality and the ease of traveling with it ( room to room or outside the house)