Citizens' rhymes with:
arkansans, artisans, citizen's, citizens, cousin's, cousins, couzens, cozzens, denizens, dozens, fisons, gazans, horizon's, horizons, imprisons, kansan's, kansans, kansans', partisans, poisons, prison's, prisons, raisins, reasons, resins, rosen's, season's, seasons, susan's, telxon's
Citizens' sounds like:
catacosinos, catacosinos's, catching, catchings, catkins, cautiousness, chastising, chautauquans, chudzinski, citizen's, citizens, cutchins, cutesiness