I always recommend Roku as the streaming device, with the exception of folks that are heavily invested in the Apple ecosystem (note, more than just an iPhone or iPad). I think Roku is a more pleasant experience with a better layout. That of course is personal preference. Both ATV and Roku work better than any BDP or TV I have used for streaming. Roku is very cheap to get into. The newer Roku sticks are pretty fast, but I always stick to the Roku 3 or 4 in the event we do not stick with IP control. Don't go with a Roku 2, it is cheaper but the interface is very slow.

Also, if you need to feed separately to an audio system (non HDMI receiver), then the Roku 4 would be a better choice, it has an optical output whereas the Roku 3 has HDMI out only.