I kind of see it like this...

Rivals

SMU- Lots of hate, Compete for the same athletes in the same region, Very different types of schools, have been playing each other since 1922 (95 years).

Developing Rivalries

UTSA- Also lots of hate, Compete for the same talent around the state, North Texas id the oldest university in the western division and UTSA is the youngest, Heartbreaking loses on both sides despite the series only being 5 years old.

Rice- The two largest cities in Texas, Very different universities (Public vs private and Largest vs. smallest in the division), Both teams have won a few, but North Texas has snagged two of their wins in dramatic fashion at the end of the game ("The Stand"-2013 & "The Stop"-2016). I'd think that irritates Rice fans just a little.

LA Tech- It is a state pride thing, and we compete for recruits in East Texas and Louisiana. I think North Texas fans have quietly resented LA Tech's ability to "do more with less", while UNT has enjoyed advantages, like size, money, and location, but have still historically struggled to be competitive for the better part of the 21st century. Thank goodness things appear to be changing.

Could and probably should be a Developing Rivalry

Southern Miss-North Texas began playing Southern Miss in 1956, which makes it the second oldest series within the division for both programs. The series is currently tied at 6-6. Despite it being a competitive series over the last 5 season, it just hasn't become a prominent match up within the western division.