The free and open-source raw converter RawTherapee has now been released in version 4.1.
I contribute myself to this project, and as I have a special interest in medium format I've contributed patches to support various MF cameras. Leaf MOS and Phase IIQ has good support, Hasselblad 3FR should be quite okay too but it has been much more difficult to get Hasselblad test files so it's not so much tested. Leica and Sinar DNGs should work of course, and various older MFD formats.
There's also native support for Adobe (Lightroom/Camera Raw) DCP profiles and Capture One ICC profiles, so if you own any of those programs you can use profiles from there if you want to.
There's now also a Mac version in addition to the usual Windows and Linux versions, but note it's built with a cross-platform GUI toolkit so it does not have a streamlined native look and feel.
I use RawTherapee a lot myself, for all my fine-art work as I like to have control. However I'm not going to lie to you and say that it's a super-smooth user-friendly software. We're doing stepwise improvements in user-friendliness, but currently I'd say that it's a quite high threshold to get into it. A key thing that makes it a bit difficult is that it's possible to develop a file in many different ways, with different color models. You can work in RGB space, in Lab space, and in CIECAM02 space, and you have many different types of tone curves to play with. Not exactly ideal to make a user-friendly software, but quite nice to have for an advanced user interested in color.
In addition to being a great raw converter once you learn it, it's also a good learning tool concerning how digital photography works. It doesn't try hard to simulate film behavior like the commercial converters, meaning that the "Neutral" profile is really neutral, and +1 on the exposure slider really is +1.
If you use a technical camera like me and need color cast correction you can do this in RawTherapee, it's called "flatfield correction". Normally this is done on a blurred LCC shot, but if you need to kill dust spots reduce "Blur Radius" to 4 (default is 32), and to kill potential tile lines reduce to 0 (or experiment with vertical/horizontal filtering). If you have a tech wide angle shot plagued with crosstalk so you get demosaicing artifacts, switch to the VNG4 demosaicer. The default demosaicer (Amaze) is very good at extracting detail, one of the best around, with the disadvantage that it can become unstable in crosstalk situations, which can be seen on some tech wides and sensor combinations.
If you work with Capture One ICC profiles note that they expect that there is a RGB curve applied with lots of highlight compression. You can provide that by applying a standard tonecurve manually.
The default profile applied when opening a file first time applies auto-tone and various fixups, and according to me it's a disaster, I never use it. Hopefully we'll make a better default to the next version, I'll fight for it
. Anyway, today I start off with the neutral profile and work from there, and I'd recommend you to do so as well.http://www.rawtherapee.com/