If we're talking on-field performance, then obviously the SEC got the better deal because OU has been a perennial playoff program and they've dominated the B12 since its inception. Texas and USC are a wash, both have been bang average or worse for a long time. UCLA's performance has been even worse than USC's.
If we are talking in terms of importance, then maybe the B1G has a better argument. Adding the 2 LA schools was certainly the more shocking development. With Texas and OU off the table, it looked like the B1G really didn't have any good options for expansion. People were looking southeast to the ACC. Virginia doesn't really move the needle, and UNC is only really good for basketball. There were also talks about adding Kansas and Iowa St. Pales in comparison to the SEC additions.
Suddenly now they added a blue blood program, maybe the most important TV market, and future expansion possibilities all along the west coast. Even talks of ND joining the fold have resurfaced. It is a massive power shift back in their favor.
IMO, there really is no clear cut winner between the 2 conferences. There are certainly losers in the PAC and B12 though. Both conferences are now without their premier brands and scrambling to see what they might be able to assemble in a "best of the rest" league.