For wood studs? I just use drywall screws most of the time.
If youre mounting to the drywall itself between the studs I use those plastic screw in anchors that are rated for like 40lbs and screws that come with them.
Like mentioned, if you are going into a wood stud, id just use a drywall screw.
If its just in dry wall i always use these. I use the zinc most of the time. But the plastic are cheaper and you can get by with. Careful if using a drill to install. You do not want it to spin to much and strip the drywall. I find a short drywall screw actually works a lot easier than than the screws they provide in these kits as well.