If you are going by crowd sizes, October is heavier than May except Memorial Day time (the weekend and a day or two after Memorial Day) is heavier than Oct, although not unbearable. First week of Oct is lighter than rest of Oct. Epcot, particularly the World Showcase in the afternoon and evening, is much more crowded in Oct than in May (food & wine is obviously more popular than flower & garden). Last week of April is about the same as May but before that last week, April is more crowded than both May and October, and insanely crowded for either of the two Easter weeks that fall in April. October would be my first choice of the ones you mention. Besides food & wine, the weather is usually close to perfect once beyond the first week of Oct and point costs are lower. First half of May would be second choice because points are lower than April and weather has usually not yet turned to the high heat and humidity that blankets the late May through Sep period.