I have a G19 with the standard fixed sights. If you are going to be shooting mostly at targets at the range, then I would recommend getting the adjustable sights....but I cannot tell you for sure whether you can get them from factory (I would assume you can). night sights are useful in lowlight situations (I have trijicons on another gun), but can be harder to see during the day.
BTW, I got the standard glock fixed sights because they are "fast" for me. I use the G19 for IDPA competitions and "putting the ball in the bucket" type of glock sights are fast for ME to acquire......you may be different.