I’m pretty into dampened switches myself. Generally, they do all involve some kind of trade-off between silence and retaining a satisfying feel - though not all the manufacturers do it the same way.
At the softest-feeling, most quiet end is Outemu (and by extension Gazzew) - especially with lubing, these will make the least noise. They also have the most “mush” to the bottom-out feel, in terms of MX-compatible options.
At the opposite end are TTC and Kailh, whose switches use more firm dampening pads - rather than being “silent”, I’d say the dampening in these switches does more to simply “take the edge off” of any harsh sounds. In a loud room, they will recede into the background. In a quiet room they will be plenty audible, but unlikely to annoy anyone. What they sacrifice in silence they gain in crispness.
Somewhere between those extremes lie most of the rest; Cherry, Gateron, JWK (who make the Shrimps). I’m honestly no fan of either Cherry or Gateron’s approach, and while JWK’s is similar, I think it’s better executed.
If silence is your priority, browse Outemu’s selection. For big tactility, you already know about the U4s. For lighter, smaller tactility, Silent Lemons might be worth a look.
If satisfying feel is the priority, I’d recommend TTC. (Kailh’s are also quite good, but may damage keycap stems - so if you swap caps with any regularity, avoid them for now.) For bigger tactility in a similar realm to U4s, check out the Silent Bluish White. For something more moderate, the Silent Brown V2 is quite good - though its spring could use an oil bath to get the most out of it.
If you’re looking for a balance, JWK is probably the way to go right now - so in this vein I’d echo recommendations for the T1 Shrimps. I don’t think JWK has a light silent tactile at the moment, but that’s probably a matter of time.
If you’d like to learn more or take a look at some comparative photos, there’s a silent switches thread here:
And here are a few recordings -
Comparing an Outemu Silent Peach and TTC Frozen Silent in a BBOX60 - an otherwise loud keyboard:
Here are tests with each of those fully populating the board:
Here are the TTC Frozen Silents in a less loud board:
Here are Gazzew U4s in a KBD67L (with badly tuned stabs):
And here are TTC Bluish Whites in the same keyboard (but with different stabs):
Always happy to chat about this stuff - so let me know if you have any questions. 