This is from an interview with Sergio about the physiques he likes:
BDJ: Physique wise, who do you consider to be the best bodybuilder?
SO: There are a few. One of the best right now is Flex Wheeler. I also like Shawn Ray and Ron Coleman. I compare myself to Flex Wheeler, a little bit. He reminds me of myself, with a tiny waist. My back was much bigger, though. He is the only one with a really complete physique.