We currently have all three, wasn't planning on it and was happy to pay for 2 services but with the free now TV movies from LG and amazon merging in to my prime subscription we aren't paying anymore than we wanted to (well not until prime is up for renewal next year). Overall they all have pros and cons, and other than netflix having to use various devices to get the best quality is a bit of a pain, current;y netflix and amazon are being run from my PS4 and now tv from my xbox 360.
Now TV is proving to be a hit though, the interface is very simple and my girlfriend finds it much easier to navigate than netflix or amazon, it's also nice it offers the linear channels as well, so it adds to our channel choice as well as supplying on demand content. When you factor in that for £4.99 a month we get 10 of skys premium channels available in 2 rooms at once it's a significant saving over having a full sky multiroom sub just to watch the one or two shows we are interested in. Paired with the now TV box in a third room we are well covered for TV now.
Netflix is still the best quality, with 5.1 and full HD it looks nicer than the other 2, it's also nice that they've not relied on certain platforms for delivery, chances are if you're device is "smart" it has netflix as an option, if it isn't on there it will be soon and that is something the others need to up their game on. I particularly like the casting element of netflix, works on chromecast, my LG Tv and PS4 and takes away the hassle of using the remote to navigate the TV menus and typing when trying to search, we just do it all on the tablet and press cast and it's done.