Since Raw has (and always will be) the flagship brand, we gave them the first pick. We used the current roster at WWE.com, with everyone on the regular roster (not NXT, sorry Samoa Joe) available regardless of health (except The Rock, who is most certainly not a current wrestler). We are also not including Triple H, Shane McMahon or The Undertaker, for similar reasons.
The start of any WWE draft has to be the WWE Champion and in this case its the guy, Roman Reigns. Like him or not, hell belong on the flagship show of the company, as its champion. For Smackdown, theyll need a star who can carry the show in his own right, especially if they decide to add another title, as has been speculated. Who better than John Cena to be the face of the brand new live WWE Smackdown then again, its The Rocks show, but I digress.