Overview
Worcester Bosch dominates UK boiler sales. Baxi is a well-respected British manufacturer (Lancashire) offering comparable quality at lower prices. Both are excellent choices.
Reliability
Worcester Bosch edges Baxi in most independent surveys. Both far outperform budget brands. The gap narrows after 8+ years in service.
Warranty
Worcester Bosch: up to 12 years. Baxi: up to 10 years. Worcester wins.
Price
Comparable Baxi models are typically £100–£200 cheaper than Worcester Bosch. Baxi wins on price.
Parts availability
Worcester Bosch has the largest UK spare parts network. Baxi's parts are also widely available — no practical difference for most homeowners.
British manufacturing
Both have UK manufacturing presence. Baxi manufactures in Lancashire; Worcester Bosch in Worcester. Both can claim British-made credentials.
Verdict
For maximum long-term reliability and warranty: Worcester Bosch. For strong reliability at a lower price: Baxi 800 is an excellent alternative.