Like the title says, what says the hive.

I shoot a Beretta 686 Onyx 20 for ptarmigan up here. I really love it. Its real pointy,fits great,is nice and light and functions flawlessly. Maybe light for dove hunting.

I used to shoot a 20 ga Ruger Red Label when I was younger. I have the 20/28 Silver Pigeon set now that I just cleaned actually, fantastic shotgun.

There are the Citori to consider as well.

I have one in 28. Great guns.

Are you looking for new or used?  Most shotgun people will tell you that in the world of O/U guns, don't go cheap.  Most everyone recommends a "B" gun -- Browning or Beretta.  

I personally try to stay away from Turkish guns.  I know some will proclaim their quality, but I have seen way too many "crapshoot" results with these to date.  Maybe it will get better.  

A friend of mine bought the Franchi Instinct L last year.  He seems to really like it.  They run about $1k

If you are in the used market, in addition to used "B" guns, you may want to take a look at the SKB made guns.  Often these were sold by Ithaca and Weatherby.  These are VERY good guns and can often be had a good prices.  I bought myself an SKB Ithaca 500 in 20ga a couple of years ago, and it has been my dove gun ever since.  The downside of some of the older guns is they may be fixed choke instead of threaded for choke tubes. (this can be remedied by a gunsmith - either installing tubes or just opening up the chokes if they are too tight)    If you shop well, you should be able to find an Ithaca SKB for $700 or less.  I picked mine up for $425.  The Weatherby guns tend to sell for more.  New SKBs are made in Turkey, so I can't really recommend them.

The Miroku made Charles Daly's are another well made used gun.  

I have a friend with the Mossberg Silver Reserve (Turkish made) -- he swears by it.  It seems ok to me, but I really prefer my Ithaca SKB.

I know this is a fairly old topic but I'll chime in.
I'm really looking forward to the release of the new 20GA Ruger Red Label!

Look for a Franchi instead. Much better guns.

Browning or Beretta.  Beretta if you are a smaller guy or want a whippy gun.  Browning if you are a bigger guy or like a little slower tracking.

Not a fan of Franchi because of the dead spot that the selector/safety can fall into.  Very annoying when a bird gets up and you go to push the safety forward and you can't pull the trigger because the safety was pushed into the dead space.

Ruger Red labels are turds.  Balance sucks for a field gun and my last had indexing issues.

If you have the money buy a caesar guerini.  Those guns are wands.

Of the ones I've used the Berettas seemed to fit me best.

Citori 725 field

Second the Beretta.  I've gotta white Onyx I took to Argentina dove hunting last year. I put over 5000 rounds through it in three days without a hiccup.  It still runs like clockwork.