I would say
QB
WR
CBs
I tried a few top RBs, but with a weak OLine and no Xfactors they werent that good
However, top WRs can beat coverage against anyone, even top DBs
Not sure OLIne matters...88s will do the trick
As for defense, go for any cards with baked in abilities. I got RoH LT and he was feasting with Edge Threat against weak OTs