You should have a clear idea of what you are going to pursue after the four years. This way you can focus on a particular college accordingly for your undergraduate degree. 

1. If you are aspiring to get placed then go for NIT Calicut. Mostly 3 to 5 core companies often visit for chemical engineering branch with very decent packages.
2. The campus life is worth living at NIT Calicut. You can enjoy various games at the hostel and special evening clubs are designed basically for holistic development. 
3. Another factor that makes NIT Calicut stand out is the politically passive environment where you can fully concentrate on your academics and engross yourself in the academics-related clubs along with some co-curricular activities.

The only disadvantage that NIT Calicut has is the weak alumni network due to the newly formed campus as compared to GEC Thrissur.

Along with the placements, the brand name of NIT when added to your resume can help you immensely for your future professional life. So think twice and consider all the factors before taking final admissions.