I have an Amazon Fire Stick and it's pretty great. It was quick and easy to set up and never lags or buffers. Occasionally, when my internet decides it's not going to cooperate, the apps I use to stream from my laptop to my Fire Stick need to buffer for a short while, but that's all. Netflix has never lagged or buffered on me. It really depends on your internet as to how well they will work for you. If you have fast enough internet, you'll be fine. Mine isn't particularly great, but it still all works fine on that end. As for those Kodi boxes, I'm not sure, although I do believe it should be essentially the same as the Fire Stick. I do have one on the way though, so hopefully I'll be able to give you a success update!