Depends on what you're doing with the camera; what kind of work.
If you are a journalist, in 135 or equivalent (and I take some liberty here) you have a few options. A pro or pro-sumer DSLR and if you need something smaller a Canon S95. Nobody cares about a little bit of barrel or pincushion. Or noise.
If you are doing "slower" journalism, an essayist, or an artist, or in Ansel Adams' phraseology, a "working practitioner" and you happen to like rangefinders, you've got a similar plethora of options.
You can buy a D300 or a D7000 from Nikon for around a grand--less if used. Superb machines. Canon offers similar solutions.
You can do stunning work with any of the Fuji F20/20/etc series.
But, if you want to put rangefinder lenses on digital bodies, and you're not going the RD/M8/M9 route, you're off into adapter land.
I earn a portion of my living shooting with Nikon products. I've used Nikon for over 30 years and I'm comfortable where the controls are. But I have a lot of experience with rangefinders - my first camera was a 4x5 with a rangefinder and I just sold the last of the M-bodies including a pair of M6TTLs. I'm trying to convince myself that that was a good idea, but I'm happy not to be dealing with film anymore.
I have a bunch of lenses left over, about half CV and half Leica, that I'm using on a Panasonic G1 as a smaller high-optical quality solution. It took about two weeks before I started getting the results I was looking for. Learning to focus using an EVF, even one as good as the Panasonic's was a challenge. The menus and location of controls is just a matter of familiarity.
But the files are great. I'm not even bothering with RAW. Screen viewing doesn't do justice, the print is the pudding, as it were, but here's an example.
Author and screenwriter Ian Adams (left).
Technical: Panasonic G1/Leitz 40mm Summicron-C 1/160 sec at f2 ISO 100
The ripper is that I'm often too close to focus with this set up. I'm used to being able to focus to about 18" or a half-metre with any of the zooms I use on the D3 bodies. The rangefinder lenses, with the exception of the ultra-wide (a CV 12mm which on the G1 gives an angle of view of approximately 24mm relative to 135 format) all stop with the plane of focus at about 36" or one metre. Yes, we can use depth of field, but...... happily the crop factor actually works well. I'm using two bodies and one has the CV 12 and the other the Leitz 40. I carry a Tele Elmarit M if I need longer. Gives me the compression of the original focal lengths but with an angle of view that is narrower. Call it roughly 24mm to 180mm in a package smaller than one D3 body.
Further irony: there is nothing in this image that couldn't have been done with the D3 and any zoom. There is no increase in sharpness in practical terms (I'm shooting wide open for a reason here and it has nothing to do with technical image quality) nor are there any straight lines compromised by the distortion inducing zooms - which I don't really care about anyway. It's an over-rated discussion by folks who can't see content.
The principle advantage of the set up is it is a little quieter. But neither the Panasonic, or the Olympus, or the M8/9 are as quiet as, wait for it, yes, the Nikon D7000. I bought one to replace a D70 and the quiet mode is, well, extremely quiet.
So I don't know. I prefer a one camera-one lens set up. If I use two in anything other than the dark, I'm now using the D3 with the 20-35 or 16-35 and the D7000 with the 28-300 which gives me AOV roughly 42ish to 450 ish. Good for some things, not so good for others.
Most of the time I'm working with one lens on the D3. Either the 80-200 2.8 or the 28-300 slow but with VR.
There is no perfect solution, but I know that I don't like having to think about where say, the exposure comp button is on different bodies - fortunately I have been able to set that up so that it's the same on every body I use--an advantage of firmware. But I also know from over thirty years of doing this that I'm happiest with one body and a good zoom and if I need more I like to stay in the same system. Means less for me or anyone else to carry and fewer compatibility issues.
That said, with relevance to the OP, any of the offerings out there will work just fine. It becomes a matter of preference. There is no real debate about image quality. Any of the pro-sumer and pro offerings are good enough for the serious photographer who is intent on making pictures. The rest is preference. Mine is not to have to sacrifice accurate framing, focus and real preview of DOF. And that is the advantage offered by the adapter-ed digital body used with good lenses, legacy or modern. You can see exactly, before you take the shot, what will be in the file.
