Skids or Wheels
Some helicopters, the Bell 222 comes to mind, seem to have retractable wheels purely for aesthetic purposes, generally driven by the marketing department.
Some observations of both systems:
Skids: cheap, lightweight, low maintenance,
Wheels: expensive, heavy, moderate maintenance.
Also, at some time the retractable wheels WILL fail to extend, either through forgetfulness or mechanical issues. This is why some operators have stand-by provisions to receive a helicopter with wheels that won't come down, usually old tyres (tires) or similar to gently land on. In these cases it is worth remembering that it isn't the landing that does the damage, rather it's the protrusions, particularly antennas and WSPS deflectors that get pushed up into the lower structure causing substantial damage.
Skid-equipped helicopters are not immune from similar issues, I've personally seen two such helicopters with fractured rear cross tubes and I can assure you that this causes similar damage to a wheels-up landing, but perhaps not so extensive.