Before buying my first Topre-switch keyboard, I read countless reviews and watched a number of videos. I was intrigued by the HHKB, but initially afraid of the layout. So, at first, I went with a compromise -- the Leopold FC660C. I liked the sound and feel of the Leopold, but at the time the keycap choices for this keyboard were limited to the stock brown and gold caps, and I didn't particularly like the layout. So, I gave the Leopold away and got a RF87UB45.
I wanted to try a heavier switch, so I got an RF87UB55. Finally, after agonizing over the seemingly alien layout, I went for a HHKB Pro 2. I liked it instantly -- the 60% form factor, the design and styling, the excellent dye-sublimated PBT keycaps, and especially the layout.
Since then, my keyboard collection has grown exponentially, and I have just about every form factor, layout, and switch type imaginable. I have an active keyboard rotation that includes quite a few boards, but I always come back to my all-time favorite, the HHKB.
All my Topre-switch boards are now lubed and silenced with my own Silencing Rings, which I think makes them even better, but the stock boards are quite nice to use as well. I have modded one of my HHKB boards to 55g domes -- it is fine, but I slightly prefer the stock 45g. I also have a Novatouch, but I prefer the RF87UB45 or RF87UB55. I have never tried a Type Heaven.
The RF87 boards provide a refined typing experience, but the HHKB is more fun. The difference between the two is sort of like driving a luxury sedan vs. a sports car.
If you happen not to like your Topre board, they have excellent resale value. You could then go for other premium switches, such as IBM Model F, IBM Model M, or various flavors of Alps and Alps clones. My own current ranking is approximately as follows:
Topre 45g ~ Topre 55g ~ IBM Model F > SKCM blue Alps ~ SKCM white Alps > IBM Model M > Matias Click > Matias Quiet> SKCM brown Alps > >> Gateron yellow >> Cherry mx red
Good luck!