I'm a big fan of ACR - I tried a lot of other converters, but Camera RAW is definetly my favourite one - it's fast, it has convenient controls, ergonomic UI, ColorChecker Calibration, and - last but not least - it's for free (from the point of view af a Photoshop owner).
The only thing that is (for me) a small inconvenience is that it renders the data exclusively to four editing spaces. I'm making a lot of photos, that are only destined to offset print. ProPhoto is a very large space (a little bit too large to my liking), and Adobe RGB doesn't cover the whole european ISO Coated v.2 space.
I know that I'm certainly overengineering it, but is there a chance that ACR will support ECI (v.1 or v.2) space in future, or should I rather forget about it?
You could use ProPhotoRGB in ACR, and write an action to convert to ECI RGB. Then use Image Processor to convert all your RAW's into TIFF/PSD at the same time running the action to convert to ECI RGB. The net result would be essentially the same as if ACR were directly outputting to ECI RGB.