My favorite switches for typing (and thus, coding) are MX blues. Unfortunately these are also the loudest, with a distinct click at each key activation. You can purchase small rubber rings that act as dampeners on each key, but this also changes the feel of the keyboard.
I'd pay well for a solution that lets me have both the tactile experience I enjoy and the sound level I need to use a mechanical keyboard at work. Until then it's bog-standard rubber domes for me.