Hm. It's not really close. "I Think I Love You" charted for a reason. But I do get the sweet nostalgia of "It's a Sunshine Day." The Brady Bunch was a better show. You can't help but smile, and think about what a funny show it was, although some of the tropes were classic. Two bedrooms and one bathroom for six kids (I'm guessing Alice and the parents each had their own). Blended family with both parents being widow/ers? Odds are pretty low, at least one divorce would have been more likely. Dad must have been a pretty bigtime architect to afford to build a home like that, support six kids, a stay-at-home wife, and pay a full-time live-in housekeeper, but then, it was the 70s so more was possible.
But, musically, Partridge Family hands down. Shirley Jones and David Cassidy were better vocalists (the little kids and Susan Dey, obviously lip-synched.)
So, "I Think I Love You," 90, "It's a Sunshine Day," 85.