Mack or A.Donald For DL

I have Mack as my DL. But Donald is on the waiver wire should I pick him up?
 LB out score DL in my league other than JJ. Watt.
 Is Donald such an elite DL he would be better to have than Mack?

Mack is now playing DE full time now, was watching to game to check.... Ray Ray Armstrong and Malcolm Smith are the full time LBs.

Generally DEs outscore DTs tho. I'd say its close but I would take Donald just for how dominant hes been since he took over the starting role. I luckily own Donald and McCoy in a full 3-4 Dynasty league and have no idea which one to trade! :)