A 68-year-old lifelong smoker with chronic cough and exertional breathlessness is diagnosed with COPD. Post-bronchodilator FEV1/FVC is 0.55 and FEV1 is 45% predicted. He has had two exacerbations requiring oral corticosteroids in the last year. According to COPD-X guidelines, which pharmacological regimen is most appropriate as maintenance therapy?