I count all the wins and losses.
The OU-Texas series is a decent analog to Ohio State-Michigan. The game has been played 115 times. Texas leads in the series 62-48-5. A 14-game lead.
I personally think of OU as the better all-time program. OU has more national championships (7 vs. 4, although both schools have received minor "national championship" recognition for other seasons which they do not claim), a higher all-time winning percentage, more Heisman Trophy winners, more conference championships, etc. OU has the longest winning streak in FBS history, and OU is the only school that has had three coaches win 100 games there.
But Texas owns the head-to-head record.
There are things I could legitimately point out to mitigate that. It is true that Texas went 8-1-1 in the first 10 games (1900-1907), and that Texas was a more established program than OU then. It is true that Texas went 17-3-1 from 1922 through 1947, and that Oklahoma was probably hit as hard as any state in the Union during the middle of that period, what with both the Dust Bowl and the Great Depression. It is true that, since the end of WWII, OU leads the series 34-33-3. It is true that, starting with the 1948 season, Bud Wilkinson's second, OU leads the series 37-33-3. It is true that, starting with Bob Stoops' arrival in Norman, OU leads the series 14-8, and that Lincoln Riley leads Texas 3-1.
But Texas owns the head-to-head record.
That grates in the heart of every Sooner fan. We all want to live for the day when we pass Texas in the series record. Meanwhile, we can think of all sorts of explanations and rationalizations, including the fact that nearly all our games with Texas have been played in the state of Texas, where, you know, the zebras are breathing Texas air and other intangible factors work against us.
But, at the end of the day, Texas owns the head-to-head record. 62-48-5.