What is the ruling on acting according to the most preponderant view in jurisprudential matters; is it obligatory or recommended? And is it permissible to act according to a less preponderant view if one is a follower (muqallid), for example, the condition of the fiancée's guardian in the marriage contract, where it is a condition according to the majority but less preponderant according to the Hanafis?

The basic principle is the obligation to act upon the preponderant opinion, and the Companions and the Salaf unanimously agreed on that. However, there is no sin upon a layperson for imitating a weak opinion if its proponent is a scholar and trustworthy, like someone who imitated Abu Hanifa regarding the validity of marriage without a guardian. In such a case, his marriage is valid, and he is not to be punished.