I have friends in both institutes, NIT Calicut and VIT Vellore. Based on their experiences, NIT Calicut is a much better choice. Although the institute does not have many permanent faculty and the faculty pool comprises only temporary and assistant professors. However, the other pros overshadow this flaw and make NIT Calicut a preferable choice to VIT.
Both the colleges will offer great opportunities so the final decision will depend on your personal preferences