Either can work, just depends on the day, the buck that sees it, and a lot of dumb luck.

Last year during pre-rut, we had ours out as a buck (Glendel Buck archery target), one single grunt sound drew the attention of 7 shooter bucks to our decoy, and they crossed 400yrds of wheat stubble to come investigate. My wife put a nice 9 pointer in the dirt.

A great tactic is to use two decoys, a buck, and a doe without its legs installed, as if she was laying on the ground around 20-40yrds in front of the buck. I've had good success with this in the past. Whether the buck is looking to get lucky, or defend his territory, you have it covered.