I prefer Supergoop, not only because it has outstanding sun protection (far better than IT's), but for me, the coverage was nicer. I may have had the wrong shade of the IT, but didn't care for the coverage or the finish, or something.
Supergoop, to me, is like a beautiful foundation. A LOT more coverage than Suntegrity's (which is about $45 anyway), and not too shiny, not too matte finish.
I got Supergoop sample sizes off of eBay to try that way, but you can get samples from Sephora or Nordstrom if you're close to one. When I tried it they only had Light/Med and Med/Dark shades, and even though the Light/Med was too dark for me, I could tell I loved the product itself. They now have a Fair shade, but not sure if there are samples for that yet.
Try the sample of Supergoop and if you don't like it, then give the IT a shot. Not sure if IT has samples, but if so, that's a great way to try the both.
Good luck and let us know what you try/like/don't like. :-)