I like the berretta S686 as far as o/u or SxS. It is the lightest O/U I've handled and I picked mine up for $500 used- I refinished the stock and now it is good as new. But I personally prefer to shoot a really crappy mossberg 9200 semi- it works better than any of my other shotguns for me and with the synthetic stock I cannot seem to hurt it.
I think a lot of shooters feel like they need a double gun becuase of all the pictures in the fashion mags. It's just not true. The best field gun is the one that fits you best and has a sight picture that allows you to get on target fast and make the shot. Rather than style, I would recommend you look at the length of pull, cast, and drop. Pick up a lot of guns and try them all out to see what fits you, balances well in your hands, and just feels comfortable. Many o/u 's are designed for shooting clays and have a very different sight picture than say a pump or a semi, and you may find that you don't like that or have a hard time learning to use it in the field.