I have some friends with some of those skis, and I have skied on quite a few as well. First off, the friend with JJs absolutely loves his. He swears that they are the best all mountain ski ever; the rip pow, groomers, crud, cliffs, ect. When I tried them, I thought that there were super fun (about 6 inches of fresh). They really want to turn, you just think it and they go. They would probably be your best choice, as the rip everywhere, are a little skinnier so easier to manage on the not pow days, and they are also super light, easy to spin on, and easy to land switch on. The friend with Bent chetlers also loves them, but they are much more of a pow specific ski. According to him, they don't do very well in crud and aren't amazing on cliffs. But that being said, in straight up pow he fucking loves them, and they are also a good ski for booters and such. The same friend demoed ON3P Billy Goats, and he thinks that they are the best ski ever, for everything, but they have a pintail, so they wont ski switch well. You should also check out the Surface One Life, they are a really really good all mountain ski, stiff for cliffs, and the massive but relatively short (they are just an angle, so it can start later on the ski and still be massive) rocker keeps you up very well in both pow or crud, forward or switch. I haven't skied the S7s or the Night trains, but I did ski on the S3s which are like a smaller version of the S7, and thought that they felt sluggish and unresponsive unless you were spinning on them.
I would say go in this order:
1. JJs-super light, versatile, fun, and a sweet ski for everything that you can think of.
2. Surface One Life- same as JJ, but stiffer
3. Bent Chetler- Similar to JJ, but wider and more symmetrical. They are pretty soft all the way through, whereas the JJ is soft in the tip and tail, but pretty stiff underfoot.
4. ON3P BIllygoat- Apparently an amazing ski, but if you plan on skiing switch much, it wouldn't be the best choice. Customer service is super good with ON3P though
5. S7-Similar to JJ, but I have no experience with it.
6. Night Train-No experience