Given the patient's history of stage 2 chronic kidney disease and proteinuria, the best next step in the management of his hypertension would be to continue with an ACE inhibitor like lisinopril (option a). ACE inhibitors are recommended as first-line agents for patients with chronic kidney disease and proteinuria due to their renal protective effects. It is important to monitor renal function and potassium levels regularly while on ACE inhibitors.