For me, out of premium plastics, MVP discs have been the easiest for me to throw lately. The last 4 tournaments I have played in were in raining conditions or the ground was saturated from a recent rain. Discraft's Z plastic was the toughest for me, but I only throw one mold in Z and that is the Pred and I used the etchings on the inner rim for grip on it. Innova's Champ plastic isn't as bad as Z, but not nearly as good as Proton or Neutron when wet or damp. Lat 64's GL and Opto plastic is somewhere between Champ and Proton/Neutron. By far the best plastic for me when wet is the soft proton in MVP putters.
Again, that is just me and YMMV. It would be nice if I could play at least one DG tournament in good weather this year...