Technically speaking, there is no casteism in Sikhism, and equality and fraternity of all human beings were emphasized by the Sikh Gurus. This is one of the reasons why the Sikh empire became invincible during the reign of Ranjit Singh and even able to defeat the formidable Afghans in Afghanistan.
Merit was given to virtues like honesty and charity.
There is an inspiring story of Guru Nanak preferring to visit and eat the food of a honest laborer and preferring it to the food of a dishonest merchant.
In Hinduism too, the Vedas emphasize the equality and fraternity of all human beings. The Manu smriti that brought about casteism was of manmade origin and had nothing to do with Vedic religion. This was perhaps necessary at a certain time period but became obsolete with time. Buddha and Mahavira too criticized casteism and emphasized equality and fraternity of all beings.
But this was all ignored and Hindus obstinately continued with the caste system rigidly, even though it was obsolete. Consequently the Hindus were weakened by disunity, and lost their sovereignty to foreign invaders for the last 1000 years. Invaders like the Mughals and British themselves were united by the ideals of equality and fraternity and this was the reason why a few of them was able to rule easily large numbers of Hindus who were much superior to them numerically.
There is a funny incident in Indian history where the portuguese invaders in south india set lower caste farmer Hindus to fight against an army of approaching upper caste warriors. The upper caste warriors ran away immediately fearing pollution by touch of lower caste Hindus,a tactic which enabled the clever Portuguese to defeat larger armies and kingdoms.
