hello suresh babu !!

its cool that you are writing both NATA as well K-CET , while in case if you get a good score in the NATA you can easily get good colleges in Karanataka on the other hand even you have chance getting seat outside of the state in case of NATA. 

Secondly coming to KCET you need to get good rank like below 10k to get top college for Arch. suppose in case if you get rank between 15-20k you will get in chance in further rounds of councelling but you need wait!!

while coming to Comedk its your choice of writing it , i mean to say choice because people write Comedk if they cant get seat in college in which they are willing to go through CET or NATA they can get through Comedk as fee structure through comedk is bit high compare to other.

so as per my suggestion you decide if are well confident that you can crack the NATA and KCET to good ranks you need not to go for Comedk.if in case if you are not well confident give try for COMEDK and one more the toughness in COMEDK is bit likely to be easy

all the best:)