I would encourage you to pick the one that interests you most! This is your last summer of high school—you should enjoy it!
Also from a college admissions standpoint, admissions officers really want to see kids that are true to themselves and take advantage of opportunities to explore and build on prior experiences as they work towards future goals (this works into your application theme). Would one of these programs support your application theme better? Only you know this.
I’m sure you know … SIP is more difficult to get in, because it requires prior research (such as completing SRA). SIP is a longer program which allows for more in depth research. However, choosing SIP over SRA is not likely to be a reason you get into the college(s) you like. So … choose the one you will enjoy.