Chronic migraine prevention — CGRP monoclonal antibodies vs topiramate vs amitriptyline, which first-line?

34F with chronic migraine (>15 headache days/month for >3 months, >8 migraine days/month). Has failed topiramate 100mg/day (poor tolerance — cognitive side effects), amitriptyline 50mg/day (weight gain), and propranolol 80mg/day (inadequate response). BMI 24, eGFR normal, no depression, not pregnant, no cardiac disease. Per AAN 2021 and ICHD-3 criteria, she qualifies for preventive therapy. Should I try CGRP monoclonal antibodies (erenumab, fremanezumab, galcanezumab) as next step? What is the evidence for CGRP mAbs vs CGRP receptor antagonists (gepants) as daily preventives?