Browning / Winchester are the same company now - and both owned by FN...but the shotguns share parts ( and chokes ) - with Browning apparently running the shotgun division.
Beretta owns Benelli and Franchi...Benelli's guns are Inertia operated / Beretta's semi-autos are all gas operated. Franchi has the inertia system - and its often debated on here and other sites whether its identical to Benelli - and I say no, but I can't prove it.
In general Brownings silver series is a solid gun in the semi-auto market. I like the Browning Silver Hunter as a good entry level all around gun.
Benelli M-2 is a solid gun / but if you buy it, buy it with the Comfort Tech recoil supression system in it ...if you go synthetic / but you cannot get the Comfort Tech system in a wood stocked gun. A wood stocked Benelli will give you at least 25% more recoil than any gas operated gun.
Browning and Beretta will give you the most gun for your money in the Over Under market. Browning's Citori line has about 30 models / Cynergy line has quite a few as well ....Beretta has at least 30 models in their O/U line as well. If a Browning Citori fits you ..then the Beretta probably will not. They are different in terms of drop at heel, comb and in general feel...the throat or grip area on Beretta's are more slender, narrow....vs more bulky on Citori - especially if the model of Citori you look at has a "palm swell".
The best all around target grade O/U - does everything really well - and fits 99.9% of the shooters out there ...is the Citori XS Skeet, 28" or 30" barrels, 12ga or 20ga with the adj comb. But new they're about $ 3,600 and selling new in my area for around $3,000.
From the XS Skeet model ...its a compromise in terms of Fit on Citori's ...maybe the 625 is the right gun for you maybe not ( but there are at least 5 versions of the 625 too - and they're different ) ...so it depends on what you're looking at. In general, I think the 625 series has too much drop at the comb to fit most shooters...making Fit a problem. Because of the amount of the drop at comb and heel ....I cannot shoot a 625 model, not any of them ! --- and I'm a big Browning Citori fan ( and own a lot of them )...
Of the guns you list ....I would probably say go with Browning silver hunter. I think its a gun you can shoot for 4 or 5 yrs ...and settle into Skeet a little and then see where the hobby takes you. You need to shoot a lot more shotguns before you jump into the $3K plus market probably ....and over time, what you like or don't like in a gun will become more apparent. Even though its an alloy receiver...I think its a decent long term gun ( 250,000 - 500,000 shells -- if you take care of it ) before you'd have to rebuild it.
If you really want to go with an O/U - the Citori XS Skeet, with adj comb, is a gun that is highly sought on the used market. So its a gun that is really easy to sell down the road if you don't like it for some reason. Its also a gun that will easily hold up to 1 Million shells or more over many generations ...with minimal maintenance.
Its the O/U I shoot, and have shot for a long time, for Skeet, Sporting clays and bird hunting....I like it in 30" barrels in both 12ga and 20ga....but buy a 12ga to make it more versatile. You can download, or buy, shells to 7/8 oz at 1150 fps for a new shooter....or go up to 1 1/8 oz at 1300 fps ...for anything you'll need to do. Now the XS Skeet is a "Target Gun" so it has 2 3/4" chambers ...you cannot shoot 3" shells in that gun ( or 3 1/2" for that matter).
Browning Silver hunter ...is a 3" chamber...at the price you listed ...but there is a 3 1/2" as well...( I don't think you need a 3 1/2" gun )....
Citori XS Skeet...