PESSAT is an exam conducted for admission in PES University while COMEDK is an exam which makes you eligible for admission in various colleges. If possible try to attend the counseling program for both of them. But if you want to select the better option in terms of fees and branch allotment then go for COMEDK counseling. COMEDK counseling will provide you selection opportunities in many colleges. So chances of admission in the preffered branch are high. Fees would vary according to your selection of college.