single coils give out the "twang" sound.. try and listen to hendrix's tracks and u'll c wat i mean.. or maybe even pink floyd.. coz roger walters uses a strat.
humbuckers give out fat and powerful sound, ideal for distortion and powerchords, and good for solos.

as for which pickup is better? it's all preference and ur type of music..

oops sorry.. mixed up there. yeah i meant dave gilmour.