Of the six factions available in Dragon Age Veilguard's character creation, I'd say the best is the Antivan Crows, mainly for their free extra potion slot, though it's a tight competition and that's only if pushed - the reality is that there is no clear standout among the six factions, and it's more contextual and about what you want to prioritize.

Excellent is the maximum Faction Strength level in Dragon Age: The Veilguard and it is unlocked by earning at least 2,900 reputation with an individual group. To earn reputation, you can sell valuables at the faction’s vendor or complete missions in the region associated with a particular faction.

The Veilguard doesn’t have the same broad, sweeping choices at the end of every chapter as its predecessors, but it does spend quite a bit of time allowing the player to figure out how they feel about their Rook.