Prestigious in what way? Football power? If that's the case, the SEC would like a word with you....
You might equal the SEC, but it wouldn't be surpassed.
Current on field performance? No, currently the SEC is better than the B1G. However, "past reputation, and achievements" are a large part of the definition of prestige.
So pertaining to this hypothetical discussion of ours, based off traditions, with the proposed additions of OU/Texas....
I would argue it surpasses the SEC in the regard....
However, from the "what have you done for me lately" department, the SEC is obviously supreme.....