How is the quality of the caps?
I was disappointed by every single caps I buyed till today.
The thick PBT dyesubed caps from Ducky (green & cream) were warped and the edges had to be smoothed out with a nail file.
The thick PBT double shot caps from Vortex via Massdrop had feelable lettering, despite beeing double shot. Not precisely produced.
The PBTs of my new Pok3r do have some warping going on and the lettering is somewhat feelable. They also do have this pin on top from production. And some of the edges had to be smoothed out with nail file. Im also guessing, the lettering won't hold forever.
The stock Ducky Shine 3 ABS caps have this coating, that feels strange to me.
Under the risk to oversimplify the explanation, the short answer for your question is this, what you have tried are key caps in the lower echelon of quality in terms of thickness and profile. The following partial list is what it is generally accepted as the relative quality of some of the most common key cap sets; however, there is a great extend of controversy on this:
OG Cherry PBT dye sub legends.
OG Cherry ABS double shot legends.
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BSP PBT dye sub legends.
GMK ABS double shot (Like GMK Carbon).
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Gateron PBT dye sub legends.
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Vortex thick PBT dye sub legeds in Cherry profile.
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All the above are Cherry profile.
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SP SA double shot
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SP DSA double shot
SP DCS double shot
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SP DSA PBT dye sub legends (Warped key caps)
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Tai Hao and Vortex double shots PBT or ABS OEM profile
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Most OEM pad printed and laser engraved ABS sets.
Besides quality, OG Cherry and BSP made key cap sets are only available in standard layouts, that do not match some custom ones like HHKB for example, that is an advantage of new sets like Carbon.