The fact remains, there are German formations more analogous to the Rangers and the Commonwealth commando units. Heck, there are units within the USMC that are more analogous to them. Either the Brandenburg Regiment, or the few Fallschirmjager units that were actually parachute-trained would make sense. To be honest, though, after further reflection, the ideal German elite infantry unit would be the Sturmpioniere - deployed in battalion strength (as per Ranger, Commando), never more than a handful of battalions at a time (fed six of them into Stalingrad), used to attack special objectives that no one else could take (as per Ranger, Commando). Special abilities in city attack, anti-infantry, and amphibious, since they were as likely as not to be bridging units in and of themselves.
For the Rangers to have paradrop capability in WW2 would be inaccurate - Rangers didn't begin parachute operations until the Korean War. Some Commando units were parachute-qualified; others weren't. In the case of the elite infantry units, it might make sense to have a range of promotions available at creation to account for the range of abilities they might display.