If you are cutting the cord and wanting to stream TV you have 5 real choices right now - Roku, Apple, Chromecast, Amazon Fire or a gaming console (Xbox/Playstation). All have their strengths and weaknesses.
Roku has been in the industry leader for a while and has the most providers signed. If you can stream it, they can probably do it. It has a nice remote and decent response time (I have the Roku2 so the 3 would be faster). They just came out with a stick version like the Chromecast which would be nice if you don't have a lot of space for the box.
Apple's design is probably the best and it had been out the longest. They should own the category if they had been a little more aggressive in signing content but it always seemed to me that they didn't want to upset the broadcasters and as a result didn't have key streamers like WatchESPN or HBOGo for a long time. They've been working hard to catch up but it's always felt like an afterthought rather than getting continuous support like Roku. If you have an Apple product like an Ipad or Iphone their system is still the simplest/best at streaming content.
Amazon Fire is set up to be used in conjunction with the Amazon Prime streaming service. Amazon Prime has made a lot of progress in the last year and is closer to Netflix than most realize but like Apple, Amazon has a bad habit of trying to get you to use only their equipment. I haven't used it but have heard it is missing quite a few key streamers (I do like Amazon Prime - they just got signed a deal to get exclusive access to all the old HBO shows like Deadwood, Sopranos, Band of Brothers and The Wire).
Xbox/Playstation are a decent alternative but only if you are a gamer and already have one. I use mine in the living room for streaming but it's too expensive if you don't play games.
Google's Chromecast is a cheap and good option but has a few issues. First you don't have a remote so anytime you want to use it you need to find you cellphone or tablet, open the app, and then pick want you want to run on your Chromecast. Second, many of the best apps can only be run from Android phones -- Iphone apps seem to be a bit of an afterthought. A last issue is the Chromecast only had 9 streaming services at launch (and only Netflix/Youtube worked well) but they did release a developer kit a few months ago and more services are being added all the time. One thing that isn't on it (and probably never will be) is Amazon Prime as Google and Amazon are both working to dominate the Android market App Store (it's too complex to explain in more detail).
I like both my Chromecast and Roku but if I had to choose, I'd go with my Roku becasue I have an Iphone. If I had an Android phone I really think I'd pick the Chromecast even with all the negatives I listed. It's cheap enough to put one in every room and the service is faster than I believe would be possible from such a small device. Apple TV is a good product but I don't think it will ever be more than an afterthought for Apple and if they start to lose market share it won't get updates.