There's a list of the available channels at their site, and some "private channel" lists posted on this site. ANY box will work well, as software (firmware) is updated automatically (and can be manually done if you're in a hurry for an update that hasn't hit your box yet.)
Biggest thing is to shop for the needs you have. Older TV? There's boxes with just standard composite video. Original box had many options (HDMI, standard video, component video, too all simultaneous).....and now the units are getting smaller. Read the features and buy for your viewing needs. Overall, a VERY good box that delivers what they promise. Keep in mind, the providers all will, at some point have difficulties which is not the fault of the Roku.
You might also join the roku forums directly. Quickets way to know what is having "issues" and what is not. (but then return here for the rest of your needs!!)
Hope you find one to enjoy!