In terms of Enrollment and Endowment, here's where CU ranks compared to the 2024 membership of the Pac-12 and the Big 12. I'm assuming the Pac-12 would add SDSU and SMU.
Enrollment: 36,430 (5th in P12 / 5th in B12)
Endowment: $2.12B (4th in P12 / 4th in B12)
On Enrollment + Endowment, only Cal and Washington surpass CU on both from the Pac. No one from the B12 surpasses CU on both. Of note, USC, UCLA and UT surpass CU on both and CU is ahead of OU on both.
(I used the conference pages on Wikipedia for Pac-12, Big 12, MWC and AAC for the data.)
Generally, what you'll see is that major private schools surpass CU for Endowment and some public schools (especially the ones with commuter components) surpass CU on Enrollment. It's rare for a school to surpass CU on both.
FWIW, compared to the current B1G, CU only beats Rutgers and Maryland on Endowment & only beats Nebraska and Northwestern on Enrollment. With the SEC, only Florida, Vanderbilt and Texas A&M beat us on Endowment. Florida, Georgia, Alabama and Texas A&M beat us on Enrollment. In the ACC, CU is behind Boston College, North Carolina, Georgia Tech, Pitt, Duke, Virginia and Notre Dame on Endowment. On Enrollment, CU trails Florida State and Georgia Tech.
So, if this means anything, I guess that when looking at these measures as an overview of resources that CU is among the upper echelon of universities with the B1G an absolute juggernaut. And by this measure, there are only 3 programs from the P12+B12+ACC with an overall better resume than CU as a potential B1G or SEC addition.