If you are looking for a reliable, widely available bottle that cuts through the bold flavors of Campari and sweet vermouth without bringing in overly floral or modern botanicals, a classic London Dry style is definitely the best choice.
The gold standard for a traditional Negroni in most bars is Beefeater or Tanqueray. Both of these are available in practically any grocery store and stick strictly to the classic, juniper-forward profile.
Beefeater is exceptionally well-balanced with clear notes of juniper, coriander, and bitter orange peel, which complements the citrus oils from the orange garnish and the herbal sweetness of the vermouth. Tanqueray brings a slightly punchier, crisper pine-juniper presence and a slightly higher proof, which helps ensure the spirit doesn't get overwhelmed by the bitterness of the Campari.
For an easy and authentic drink after work, grab a standard bottle of either Beefeater or Tanqueray. Measure out equal parts gin, Campari, and sweet vermouth, stir well over ice, and garnish with an orange peel.