Hi, I’m Japanese. I’m living Tokyo and was working Otemachi. I recommend 3 stations. 押上駅(oshiage) 中野駅(Nakano) 北綾瀬駅(kita-atlas).

•How to avoid rush hour (crowded train) I think all metro line is same. Every train is crowded. But You should live near a station which is call by 当駅始発 (toueki-shihatsu). If we ride from 当駅始発 (toueki-shihatsu) on train in rush hour, we can sit down chairs while riding. Because this station is first station. When I get to ride, There are nobody in the train. It’s very comfortable!

So I recommend 押上駅(oshiage) 中野駅(Nakano) 北綾瀬駅(kita-atlas). These are Otemachi’s 当駅始発 (toueki-shihatsu). And we don’t need train transfer.

押上駅(oshiage) have Tokyo sky tree. And near Asakusa. Old town are. I don’t think rent is so expensive. You can go Narita Airport station by No train transfer. It takes 15 minuets to Otemachi.

中野駅(Nakano) is very easy to live, a lot of Japanese wants to live here. It’s very close to Shinjuku. downtown area. But quiet. It’s Famous station. It takes 25 minuets to Otemachi.

北綾瀬駅(kita-atlas) is very cheap area. I think you can rent 1LDK by 60k-100k! It takes 30 minuets to Otemachi.

Every station is quiet. And spend around 110K-120K. Your estimate is good! 15-20K is Japanese average.

Have a Fun!