It all depends on your priorities. Both are elegant universities. One has been around for decades, while the other is newer but has been centrally funded and logistically developed.
AIIMS Advantages:
Good infrastructure, high-quality academics, and low fees. If you prefer a little privacy, single-room hostels are available. AIIMS exams and curriculum are up to date (taking students' wishes into consideration). You are not required to follow university-imposed rules and schedules (the director is in power, and students can easily approach him). It has a lot of funding and research opportunities. A clean and well-kept hospital, Better anti-ragging policies, no campus politics, and other such issues.
Calicut Medical College Advantages:
It has a well-known atmosphere (climate and language), homely food and delicacies, a little less loss in terms of academics, and campus politics if you like that sort of thing. CMC Calicut is more familiar to the general public than AIIMS Raipur. Cultural festivals such as Onam, Diwali, Eid, and Christmas are far more organized.