That's a very good question--with games costing $50-$60 nowadays, I tend to only pick the ones that I have at least some idea if I'll like or not.
For that reason, I think it was Apollo Justice--I didn't read the reviews because I knew I'd enjoy it, based on series pedigree alone.
Oh! It might have been Spore, but I can't remember if I read any reviews or just bought it because I liked the Creature Creator...