The problem with shaving and trimming pubic hair is that the area "down there" has uneven skin with lumps and bumps and folds. The skin here has many more nerve endings than on the face. This is why it hurts like crazy when using a regular face shaver or other hair removal method on your private parts. My suggestion is to get a micro trimmer, as this is ideal for detailing the difficult to reach areas, like the bikini line or genitals. A beard trimmer won't work as this is bigger and broader and difficult to maneuver in tight spaces. The round nose hair trimmers are not able to deal with brows, ear hair and bikini lines.
The micro trimmer of course can groom and trim all of these areas and so this trimmer has the edge so to speak. Any quality micro trimmer will have rounded teeth on the blades and so it will not cut and nick the skin like other trimmers. There are a gazillion micro trimmers in stores, on TV and online. Many are cheap plastic with poor quality blades that tend to pull hair rather than cut it.
Most micro trimmers do NOT have replaceable blades. So you have to trash the trimmer when the blades become blunt and dull, and buy a new one. So any trimmer with replaceable titantium blades the obvious best buy by far.
Any trimmer of course will only cut back hair to short stubble length. If you want to have bare, smooth skin, investigate electric personal shavers as these are designed to give a long lasting smooth shave, with no nicks, shaver bumps or ingrown hairs. Search for "pubic shavers" or personal shavers and you will find a good selection. These sensitive skin shavers are far safer and cost half as much as a waxing and about 10% of the laser / IPL type hair removal methods which also do not produce permanent hair removal, as many claim.