I've just been to Zao once. For one day. Admittedly the weather was cack, bad visibility all morning. However, it was bright in the afternoon and we still thought it was pants. Basically, lots of really short runs connected by short lifts that are too far apart so you have to spend a lot of time scooting between them. I spent the whole day feeling like I was in transit - trying to get to the decent runs. Of which
Appi is a bit more how I like it. It's split into two areas that are easy to travel between. The gondola and lift set-up is good, they are fast and well placed.
There are a lot of long, pretty steep runs for full-blown maching. There are also medium and learner runs. It caters for everyone. There are some good tree runs between pistes and some really nice runs under the lifts. Watch out for patrol. We met a canuck there
Tenjin. I too have heard lots of really good things about this place.
Firstly, the marked runs are very, very short and hardly in abundance. But people go to tenjin to ride the bc. From what I've seen it's good in comparison to anything else in gunma, there are good, steep-ish slopes in very close proximity to the chair-lift. Patrol were really lax when I have been.
Tenjin also gets good snow consistently, from what I've heard. So, if you get there
Basically, yanaba is a jibber's wet dream. It consists of one main run with a shed load of decent, well maintained kickers and jibs of all shapes and sizes. There are a few peripheral runs with no jibs but they are short and a bit of a token gesture, I think. 90% of the clientelle are young snowboarders riding said jibs. 87% of all statistics are made up on the spot.... there is not much else to it.