Yes, agreed. Future World never feels crowded to us even on busier days. OP, if it's crowded, you'll feel it most walking through WS and, certainly, standby lines might be longer. If I were there on Memorial Day, EP is the park I would choose as there is so much to do other than riding rides.
Holiday weekends are practically ALWAYS busy at the parks, expect heavier than normal crowds and plan for a full day park visit. With that said, as stated by pp, Epcot generally holds and disperses crowds the best compared to other WDW parks due to it's expansive layout and wide walkways all around the park. MK on the other hand will likely be at least visibly the busiest. Epcot is hence definitely the better option!