Most Helpful Guy
I think the most common if for women to like six packs and moderately large muscles and for men to like slim waist with moderately large boobs and butt.
The next most common for both is probably to like slimmer than that - lean muscles on men or a petite woman with small perky boobs and butt. And then a few people like 'bigger is better' on either. Since neither huge muscles or huge curves are common, people with them will be quite popular even though it's not most people's favourite - more people like each then have that body.
Finally a few people do genuinely like overweight - but far fewer than actually are overweight.
Most Helpful Girl
I don't find physical attraction with big burly superhero-big guys, but from athletic (more soccer player, less linebacker), to average to even kind of lanky/skinny (like male fashion models; notice that they are often skinny but almost never bony). And to be frank, not into an overweight guy. If he's working on it fine, but I prefer someone at least generally healthy.