Well ATLA will forever be the best no doubt, that being said LOK is not that bad at all it will keep you entertained with battles, good animations, and some intensity to the stories. The important thing in LOK is about growth, a young girl who is carrying the name of the Avatar and have to live up to expectations and to watch her grow and mature while becoming a great Avatar was awesome. For those who want action most of the time, this is not it, this is more listen to understand the type of thing. One thing that really annoyed me, for the most part, was how they made the avatar looked so weak, I mean the Avatar should be a respected being because it's the Avatar, I know it's not about raw power alone but Aang wasn't weak at all yes he needed help from friends and past life's but Korra gets beaten easily by anyone even in the Avatar state, otherwise, it's nice to watch.
Personally, I think the paying attention to kung fu style differences and the respect to each kingdom is what made the first series so great because the second round Korra had a lot of plot holes and really didn't pay attention to the advancement of each style when it came to 70 years later.