If you can find one at a fair price, a good first double would be a Savage Stevens Model 311, or a Rossi, or a "Universal Baliki Toz 66" (Russian, imported by Universal, true sidelock with "rabbit ear" hammers, very high quality and fit for the price. Even has hard chromed bores!)
My first OU was a IZH27 12ga, great gun at first but I started having trouble out of it. But at the time I was shooting alot of clays. I put almost 10,000 rounds out of that gun in just under 3 months. I then bought a Stoger Uplander 20ga but it was cyl. bore choked and wouldnt hold a pattern for me to kill a rabbit. I also owned a Mossberg Silver Reserve 28ga and it was a good gun, but I got itching for something new and had no money so I traded it off. Currently I own a EAA/Baikal IZH-43K 12ga SxS, single trigger and screw in chokes nice gun it kills on both ends but Im working to resolve that some. Tryin to find a good formula for some 7/8oz loads.
IMO, the bottom line depends on your budget and what your going to use it for. All of the above mentioned guns are fine field guns, price pretty much at $400 or less. However if your going to shot alot of clays with this gun and your budget allows you to spend the money I strongly suggest a Browning or Beretta OU. Doesnt matter what model they are imo the best $1000 dollar double on the market. Never owned one my budget hasnt allowed it yet. But I have shot both.