If you can afford a fine bespoke English Double they are like a work of art. But most of us cannot afford to spend $100,000 on a rifle, for me the divorce would be way to expensive.
There are many good Double Rifle choices available to shooters today. Starting on the lower end and working up you have Sabatti, Blaser, Merkel, Chapuis, Kreighoff, Verney-Carron, Searcy, and Heym. Several of the rifles in the middle are interchangeable in order in terms of price and quality.
The jury is still out IMO on Sabbatti. It is very inexpensive in the world of doubles. Some owners have endured endless problems and others love them. I believe it is the luck of the draw.
Blaser is a little different in that it has a cocking device in lieu of a safety. It requires more force to push it forward but can be carried more safely as the the gun is not cocked. There are several other items that are not conventional such as the way the barrels are regulated. These guns tend to be accurate and very strong. One main drawback is the gun must be recocked after each reloading. In a Dangerous Game charge it could be interesting.
Merkel and Chapuis offer some very nice rifles that are of a more traditional design than the Blaser at a very attractive price. Owners of these rifles are typically very pleased with the rifles.
I own a Krieghoff. It has a cocking device similar to the Blaser, only it remains cocked after reloading. It is a good solid accurate rifle and I would recommend it without hesitation. It is also offered in the 500-416 which I will get to later.
Krieghoff International Inc.
Verney-Carron is a very old French company and builds some very nice rifles. Kebco imports them in the US and Ken is a good guy.
Kebco LLC
Searcy is American made. Butch is building some really fine rifles and is offering some very good deals on some nice rifles. Excellent customer service.
B. Searcy & Co.
Heym is a German built rifle. Chris Sells imports them and is another first class guy. These are very nice rifles.
HEYM USA
Caliber/cartridge can always invoke interesting conversations. I prefer a rimmed cartridge. Rimless work, it is just my preference.
If I was buying a dedicated elephant rifle it would be a 500 or 577 Nitro.
Buffalo/Elephant rifle would be a 470 or 450 Nitro. We can argue until we are blue in the face which one is better but is splitting hairs on things like bullet availability and which is more common in Africa. They are both very good.
A 375 Flanged or 450-400 would be a great buffalo rifle, can kill an elephant deader than a doornail, and can be scoped to make a pleasant plainsgame rifle. The 9.3 by 74 fits this bill but is a little small IMO for elephant.
Which brings me to the 500-416. It is relativley new and looked down on by some "traditionalist" but offers original 416 Rigby ballistics in a double rifle. In some ways it could be one of the best choices.
Then there are ejectors and extractors. Some of the makes above offer both, other either one or the other. The choice between the two offers endless hours of debate on forums.
Try to attend a show like SCI or Dallas Safari Club where you could handle multiple rifle and see which one fits and feels you the best. You can order custom stocks from most makers and can be measured at the shows. Fit and feel is more important to me than if the rifle has ejectors or not. It is everything when shooting a double.
As mentioned earlier I own a Krieghoff in a 470 Nitro and a Boswell in a 450-400 3 1/4" (circa 1905). I love them both even though they are quite different. I am thinking about a 577 Nitro and 375 Flanged as my next doubles.
Hopefully all of this dribble helps a little.