I think, as others have said, it depends on board size, for one.
I also find that it depends on switches, also.
I like top-mount with a good polycarb plate. That's KBD8X MKII with aftermarket plate, right? I've got that with lubed Everglide Jade Green, and it's great. I hear that top-mount is better for tactiles. Makes them more crisp, or something.
What I do find is that top-mount is more consistent for tactiles. They can be noisy, but you can get a more consistent actuation and sound across the board using top-mount as opposed to tray-mount.
What about plateless? I have an NCR-80 with Ergo Clears, and it's okay. I can see what people mean by tiring. The travel seems a little longer, even though it isn't. And you feel the bottom if you strike it. Case construction of NCR feels and sounds like a cardboard egg carton. Well, mine's tape modded, so it's a particularly thocky egg carton.
Anyway, I'd like to try polished MX Browns in an NCR-80 before passing final judgement on plateless. It's viable at near TKL level [75% or so]. Doesn't feel too mushy or catastrophic.
Haven't typed on KBD67 Lite recently. But the mounting system is better than tray-mount for both linears and tactiles. JWK-style switches seemed to benefit from it more than Cherry did. I wouldn't say is was as crisp as the top-mount on the KBD8X MKII, but it is very versatile, and good enough. Maybe a bit stiffer, closer to a tight tray-mount in that regard.
So far, I think I prefer top-mount, esp. with softer plate, for tactiles. But it's not always the answer. Lubed KTT Mallo works fine in a stock MK870, which is just tray-mount. Sounds a bit better with the steel plate, too, better than the polycarb mod.