The second steer looks to have more natural width, muscling as well as capacity. Other things to consider how they move, should be nice and smooth, track well, toes point in the right direction and all his joints should move freely, any joint type issue will only be magnified as they pack on the weight. From there you want a good angle to his shoulder, a straight top line and a good hip, and above all balance in his appearance. Hard to find one that is perfect but you want their assets to out weigh their detractors.
The sooner you get him on feed the better; they will stouten up and have that look you want in the ring, the longer their not on feed the rangier they seem to look at the end.
When selecting calves we always start at the ground and work our way up, if they do not move right, there is no need to go any further with them. You want that calf that catches your eye over and over as you evaluate them, just as long as he has the right part and moves well in a closer evaluation.
We see it at sales a calf has a huge rear end (and that is about it) and kids will get stuck on it for that one attribute without looking closer for issues.
Both calves look they have room to grow so whatever she does decide on I hope she has fun and does well.