For whatever its worth, I'm now on YoutubeTV. (I had been using Hulu with Live TV and streaming the Sox in ways prohibited without the express written consent of Major League Baseball). The Hulu interface is a mess, and performance was not great on my middling broadband connection.
Out of all that I've tried, I'd rank them like this:
Price (including local channels and HBO):
1. DirecTV Now
2 (tie): Hulu with Live TV, YouTubeTV
3. PlayStation Vue (highest price and the fewest local channels)
Apps/Interface
1. YoutubeTV
Youtube nailed it here. The typeface is great. The menus are readable. It's easy to find live TV and favorite shows. The channel surfing experience is the most like actual cable, and it's easy to switch back and forth between shows you were previously watching. In a nice touch, if you switch between shows (say, PTI and the news), it'll pause the first show automatically and resume where you left off when you switch back.
2. DirecTV Now
3. PlayStation Vue (it's actually quite good on iOS and PlayStation. The Roku app is functional, but clunky)
4. Hulu with Live TV (it's very polished, but actually finding content is a chore. There's layers upon layers of redundantly named menus that do different things. Also, there's no discernible pattern regarding which shows allow rewinding and starting from the beginning).
DVR
1. Hulu with Live TV (it's an actual DVR. You get 60 hours and you can record things indefinitely)
2. YoutubeTV
3. PlayStation Vue (Youtube and Vue are identical. You get unlimited recordings but they expire after a set period of time. Youtube's recordings last longer)
Performance
1. It's too early to tell, but I've been watching for a couple hours and have had no hiccups and HD picture with YoutubeTV.
2. PlayStation Vue. Totally reliable.
3. Hulu with Live TV (it was watchable, but the video would hiccup regularly. Sound would drop and the picture would jutter).
4. DirecTV Now. Utterly unwatchable.
NESN
Youtube TV and PlayStation Vue are it for viewers in New England.
So far I'm a happy customer with Youtube TV. Seems to strike the right balance between price, performance, and UI. The $40 base package gets me several channels, including local ABC, CBS, NBC and Fox and NESN. I'll add a HBO Now subscription while John Oliver and Westworld are in season.