For my situation, I'd recommend the 2016 Roku Streaming Stick, though I should caveat that this is my only/first streaming device so far. I stream Sling TV through it and it's quite amazing.

I have 100Mbps internet and this Roku is for WiFi use only as it has no ethernet port in it. I've speed tested my router (Netgear Nighthawk AC 1700) a few times and it routinely pushes WiFi signals around 78Mbps, and I bought that router specifically to ensure the signals are pushed at higher speeds and over the 5Ghz frequency to not be interfered with by other routers that neighbors have.

Now be advised, your router quality is everything when pushing signal like Sling. If you have an older router, your signal might be jammed up because of the signal frequency (2.4 Ghz) that every older router now uses, or not being kept up with by the router itself...you may have 200Mbps internet but if the router is old, the speed quality might not be up to par. In this case, I'd seriously consider upgrading your router...if you use WiFi heavily, you won't regret it.

Hope this helps!