I'm currently watching Arslen Senki. It's got a fairly immersive world and a pretty good plot so far. It's nothing new, but it's execution is great.
It's one of the only series I can watch that's not based around romance, which speaks for how good it is at what it does.
Also, the characters are a great bunch, I personally like them all. Most series, there's a couple of tolerable characters, but in this case, even the enemies are justified.
If you liked Avatar the last Airbender, this series won't disappoint.
Also, it's second season started today, so there's that.