I don’t have experience with those particular boards, but others here do.
If you perform a search for Keychron keyboards of the model you are looking for, you will find information.
Generally, people here seem satisfied with the Keychron Q-series, or alternatively the V-series as a budget option.
The Keychrons come pretty much ready-to-use. You can adjust dampening, choose the plate material, lube the stabilizers, and so on, but you don’t necessarily need to. The Q series feels a little more ‘luxury’ because of the metal case and the basic gasket system. The V-series is built more like a solid pre-built, it is a tray-mount so there will be a slight auditory difference from the Q-series. [Plus the case material will make a difference.]
The Monsgeek needs some final-assembly, that’s my understanding. At least the stabilizers. They have ample dampening options, so it’s up to you whether it will be a quiet or resonant keyboard. I would get a Keychron if planning to do no work on it, or a Monsgeek if planning to do some customization.
If going for a custom, there are some mid-tier options that are pretty decent. I think KBD8X MKIII is coming into stock. Nice top-mount. I have the MK II. It doesn’t have many special features, but the mounting and sometimes the sound characteristics are pretty solid. As is the PCB. But it doesn’t have adjustable feet, so the typing angle is fixed.
The Frog TKL is good if you can get one, especially with a PCB included. The “tadpole” mounting system allows for flexibility on the part of the builder, and is good for different types of switches. I would definitely get one if it were convenient.
The Zoom TKL is said to be a good budget custom. That one comes in many colours, doesn’t it?
It’s too bad that you recently missed a BF-week sale on the HMKB, a steel TKL. It was significantly discounted. But you’d have to produce a custom plate for that one, unless you like steel / brass.
The Monsgeek M3 is out of my budget at the moment, and I’ve got to live with that, even though it is $150 CAD shipped right now. It would be exactly what I need for Gateron G Pro Brown 3.0, I expect.