Picking a gun for a serious competition shooter like you - that might fire 30,000 shells a yr ( 1,200 boxes)......or a guy like some of us that just want to have fun - but still shoot 15,000 shells a year (600 boxes) or so ....or a guy that just wants to shoots some clays once in a while - that might fire 2,000 shells a year ( 80 boxes)...are very different things.
If I had to list the top 5 O/U mfg's as I see them ( and with full disclosure / I have about 13 Browning O/U's - all Citori's and all Miroku guns - in my safe today ...5 field guns - Lightning's, 2 -XT Trap models, 5 - XS Skeet models and a BT-100 )....but I buy Browning Citori's because they fit me / and I like their fit and finish - and I wanted stand alone guns in every gague vs a better competition system like carrier barrels and tubes ).... but having said that ....my top 6 would be:
1. Krieghoff
2. Kolar
3. Blaser
4. Perazzi
5. Browning
6. Beretta
I don't think there is a bad gun in the mix / and any gun made by those 6 companies will easily be a 500,000 shell gun before you have to consider any major rebuilds...if even then ...
For a pedestrian shooter like myself ...that won a few tournaments and state titles ( in class, never overall !!! ) in sporting clays ...I fall easily into that middle group of shooters just out to have some fun ...and shoot 15,000 shells a yr or so. Any of the guns from Browning or Beretta will meet my needs ( but we buy what fits us / and at 6'5" and 275 lbs - what fits me / vs zippy or Oneounce might be very different).
In that top 4 ...the Blaser's are getting a lot of attention .../ but nobody knows where it may end up ...or who may buy them out or whatever may happen. All of the top 4 are big time players ..and big time shooters are sponsored by one of them / and hopefully you will be someday as well ...and then they'll tell you what you'll be shooting. In the meantime --- a Blaser is not a bad choice ...but neither are any of the top 6 ...in my view.
Oneounce likes the Belgium made Brownings a lot more than I do / and he likes CG and Zoli as well - way more than I do ..../ but I'd probably put them in 7th or 8th on my list .../ but like Slugo said too ...its just my 2 cents. But what I do know ...if you're going to shoot sporting ..seriously / or Skeet ...then you need to consider a Carrier Barrel gun / and a company that will fine tune your fit - and your triggers to your liking.
My primary guns are the Citori XS Skeet models - 30" barrels, adj combs ..at around 8 1/2 lbs ...in 12ga, 20ga, 28ga and .410 ...and I shoot them for sporting, skeet and some field hunting. For Trap I go to a longer and heavier gun - Citori XT Trap in a 32" and around 10 lbs. I have a nice BT-100 ...but rarely shoot it / and I'll probably sell it ..but those are my go to guns.
But if I had enought talent - and was 30 yrs younger - I'd invest in one of the top 4 mfg's - with a carrier barrel / even if I shot the 12ga 90% of the time in sporting ( only the bigger shoots - like state tournaments out here have any sub-gague events ). But I'm not going to drop $ 35 K on a new gun ....when I only shoot 1/3 of the guns in my safe now ...and for me today, breaking 70 on a sporting course is a good day for me / or in the low 90's at skeet / or mid 90's in Trap ....its just how it is / as most of us get into our 60's and the eyesight goes ....and shoulders, and elbows, and feet...( and hemmeroids ..just kidding ) ...