Quality, Durability - and Price ... Even though prices are up / you still get a lot of gun for your money / and a gun that will easily shoot 100,000 shells or more without any major problems.
I also like the look of the Browning Citori vs a lot of other O/U's. That isn't to say that Beretta ( probably their primary competitor ) doesn't make very good guns as well.
The #1 reason I like the Citori - is Fit. I have figured out over time that the high combed guns that Browning makes - the parallel comb guns - like the XS Skeet and XT Trap are the models that fit me the best. Other than the DT-10 model, Beretta doesn't really make a gun that will "Fit" me.
I've been shooting Browning Citori's / in one model or another / for about 35 yrs ( and I maintain my guns / take stocks off every 6 months / change springs and firing pins as necessary, etc ) but I've never had a Citori fail me in a tournament.
My primary guns for Skeet, Sporting and bird hunting are the XS Skeet models / in 12, 20, 28ga or .410 / all 30" barrels .
My primary Trap guns are the XT Trap ( 32" barrels ).
I have a few other Citori's like the BT-100 single barrel trap gun / and a few Lightning models in 12 and 20ga ....but the XS-Skeet and the XT-Trap are my go-to guns as far as O/U's are concerned.