'Pride and Prejudice' might seem like the obvious choice, but I'd actually recommend 'Emma' for first-time readers of Austen in English. The protagonist's misadventures in matchmaking provide a clear through-line that makes the social commentary more accessible.
What makes 'Emma' work so well is how Austen structures the misunderstandings. Unlike Elizabeth Bennet's sharp wit, Emma Woodhouse's flaws are immediately visible, which creates a gentler learning curve for readers new to Regency-era vocabulary. The humor translates surprisingly well even with cultural barriers.
The village setting also simplifies the social dynamics compared to Austen's other works. You don't need to decode complex family relationships or London society hierarchies - just follow Emma's often disastrous attempts at playing Cupid while picking up period-specific language naturally through context.