GOOD QUESTION. There are SO many students who mistakenly think that being well-rounded beats having a spike in one area and they are unfortunately wrong. So to answer your question, it is better to have a small list of EC’s that directly relate to your intended major. Not only does this show your commitment to these few ECs (which by simple math shows you spend more time on these few ECs rather than dabbling in many) and also displays your interest in a certain area. Hope this helped! 
Could you chance me back here? http://talk.collegeconfidential.com/what-my-chances/1995754-chance-me-low-gpa-rank-cornell-rice-wash-u-ucla-etc-p1.html