Firstly, very nice looking room you have! Second, you do realize how large the PB16 Ultra is, right? It's very large and very heavy. The VTF15h mk2 is a handful, but the PB16 needs a plan, it needs a place to stay and a plan to get it there. It's 175 lbs and 200 lbs shipped. It's a very nice sub, but you ought to to a mockup of its size and think about where it can go and how it will fit in there.
The VTF15h mk2 is large, not as large as the PB16, and not nearly as heavy, but it is still a two-man job to move one around, as opposed to the PB16 which not even two men can really handle safely. The PB16 has to be slid around on furniture sliders or some kind of heavy-duty dolly. Two VTF15h mk2s would be able to match the PB16's deep bass performance and would certainly outperform it above 40 Hz. Plus, two subs can do a better job of getting more even bass throughout the room than a single sub, so there is a lot of advantages here. The downside is two VTF15h mk2s will take up more floorspace. Again, you ought to do a mockup of its size to get an idea of how big it really is.
Two Rythmik E15HPs will be the easiest to handle and take up the least amount of floorspace. They will look the nicest if you get them in gloss black. The problem is they are sealed subwoofers, so they will not have the deep bass output of a PB16 or even a single VTF15h mk2. A E15HP could probably come close to a VTF15h mk2 or PB16 in output above 50 Hz or so, but below that, it will not be able to compete. If you are interested in deep bass, stick with ported subwoofers. If you are interested in subs from Rythmik, I would be looking at the FV15HP or FVX15.