My collection of Topre-switch keyboards includes HHKB Pro 2, HHHK Pro 2 w/ 55g domes, RF87UB45, RF87UB55, and Novatouch. I have installed Silencing Rings in all of them. The last one I silenced was a RF87UB55 -- on this one, I also lubed the stabilizers and slider rails on all the switches and put rubber shock absorbers under the spacebar. This silenced/lubed RF has become my favorite board with respect to the overall refinement and solidity of its sound and feel.
However, I still prefer the 60% form factor and layout of my HHKB Pro 2 boards, and I enjoy the springy feel of the case-mounted switches.
The Novatouch benefits the most from silencing, and I also like the novelty of being able to put Cherry mx caps on my Novatouch. However, I have found that in order to avoid bottoming-out noise on the Novatouch, it is best to use OEM or SA profile keycaps. This limits the choices among mx keycap sets.
I have the luxury of keeping all these boards and putting them in my rotation for variety. However, if I had to rank-order them, it would be something like the following (all are silenced):
RF87UB55 > RF87UB45 ~ HHKB Pro 2 55 ~ HHKB Pro 2 45 > Novatouch
It is difficult for me to rank these boards, because there is something to like about each of them.