I have looked at the Tello on and off for awhile because it is supposed to be programmable in Go (https://gobot.io/documentation/platforms/tello/). Your impression seems negative, can you elaborate?
Sorry if that came over as negative. I really like what they did with it. I am using it in python and getting a video stream into OpenCV and sending commands to the drone is stupidly simple.
If you are on the fence I'd say just buy it, it's quite cheap and is great for experimenting.
The reasons why I would like something like the Avata are:
* I want something that does not rely on Wifi but has their own transmission system (DJI is really top of the market here) because it should fly around a two story house where I can't guarantee coverage
* and I don't want to deal with switching networks (the goal will be switching between multiple houses and flying the route recorded for that specific house)
* and a better camera (the Tello is a toy camera). I would go for adding a naked GoPro but that's a hack
* and if all stars align, something that has indoor path following already built in
