At the time Bitcoin was invented PoS, PoD, PoE, did not yet exist.
Having said that PoW is arguably still the most secure today. The most popular PoW alternative today. PoS will always arguably be vulnerable due to the "Nothing at Stake" problem:
"The point is this: even if stakeholders are bonding coins with a large market value, in a way that they will lose the coins if they behave dishonestly, this is only a deterrent to dishonest behaviour until they move their coins, which, being an event in the future (both in realtime and blocktime), is necessarily not something that can be detected at the the current point in blocktime. So cheap histories, or “costless simulation”, are not something that can be prevented while only bonding value defined inside the system"