We've had the plastic grooved type and although some are very good others go brittle and can be tough to get out of the ground ..... we now use a mixture of both metal and plastic. We have rock pegs too and use them for the storm strap no matter what type of ground we're on. We carry a box with all types in but to be honest just put whatever we grab out of the top first in, our box needs a tidy as we have some broken plastic pegs and some bent metal pegs that we keep carrying around ...... I think when we've got rid of them then the box is going to need restocking
Can't decide which to get this time around though, it's a good few years since we bought pegs.