I guess I would have to say TKM since students usually choose TKM after CAT and CET in Trivandrum. I can guarantee that you will get good quality education in TKM in terms of work and the number of juries and field trips. It has certain drawbacks of being an aided college as opposed to GECT which is a government college. If your concern is purely about academics you can't go wrong in choosing TKM. Try to get more information about the life of an architecture student at TKM and GECT. Good luck.