I really like Gaither but I don't love his fit at RT. He is a very good pass protector but doesn't get much drive in the run game. Andre Smith is a perfect fit on the right side. By all accounts, he looked really good in his limited time last year. He is so talented and will be such a force in the run game, I really believe that he is going to thrive at RT in his first season as a full-time starter.
I dont think RT would be much of a problem for Gaither. Might not be great right off the bat but I think he could be very successful there and with Andre having limited experience he gets my vote as of now. That said, Andre was pretty darn impressive in the few snaps he did get and I have every faith that he will be a great one if he can keep it all together. Down the road I have a feeling he would be the one to get my vote.