I've been to many Texas vs ou games, many games at DKR (season ticket holder for almost 40 yrs now) and saw Texas play LSU in the Cotton Bowl when Simms was a senior.
Based on the above, I would go to Texas vs LSU this year. Simply because Texas and ou play every year, LSU doesn't visit Austin that often.
Sad thing is I wont be able to attend the Texas vs LSU game this year but my daughter gets my tickets. Hope you're able to score some!