All makers can produce lenses with superb sharpness - go through each range and there they are. But this not a contest worth winning, once all lenses achieve a certain threshold.
If fine images are your goal, use lenses that get you there - those with high impact, balance, color, bokeh. I prefer the B85 rendering to that of the technical best 85mm (and best overall by most accounts) lens ever made for 35mm photography - the Otus. But for anyone who just shelled out $4500 for an Otus, it would be sacrilege to say so. ;-)
Sony and Zeiss have realized all this, so you see this well-developed character in all their modern FE primes. No one makes anything like the FE 35/1.4, it's an achievement so good that if it was a C/N lens, people would be doing back flips. Before long, it will be driving reviewers crazy that they cannot use FE/Loxia/Batis lenses on any other platform. The '
sharpness uber alles' crowd like the Sigma; not everyone sees lens drawing styles as important.
What can be an issue is that character lenses are generally narrow in scope, and this is true of the FE 35/1.4 and golden oldies like Canon's f1.2 lenses, and Nikon's new 58/1.4.
The Batis pair are true Zeiss in that they suffer no such compromises. Like the RX1 Sonnar, they are up for any fight at any aperture in any environment. These are hallmarks of Zeiss through their long history.
On comparing across FLs - you can't. The rule of thumb is this: the longer the focal length the stronger the lens performance. The 'best' lenses are mid-long telephotos, then in the regular FL ranges most use, it's 85-100, then 75, 55-60, then 45-50, then 35 and so on. So traditionally, designers aim for strong centers in wider lenses to compensate.
The FE55, good as it is, cannot match the B85, and the FE35/1.4 cannot match the FE55 except in one huge respect - center performance, where it does better below f4. From f4 on, the FE55 walks away from it all over the frame.
thanks for your remarks. We are very lucky to be using Sony, if only for the lenses. Reviewers often carry large biases towards established market participants, and that is understandable.
For example, the Photozone site has still not tested the FE55, two years after release and it being the mainstay of the range. In fact, they have only tested ONE FE prime. Not many Canon users will want to know about FE. It's only bad news for them...Zeiss had great success with the ZE range, so much so it's now morphed into Milvis. Many people don't like Canon's color balance but Zeiss made the ZEs work so well they delivered far superior results - on the same sensors. So it's the EF lenses as well.
Here are some images to illustrate this point.
Test of new Tamron prime lenses on Canon 6D - see if you would be happy with the woman's complexion and lack of tonal range in other images - most un-Sony like:
http://photo.net/equipment/tamron/sp35_sp45_review/
(scroll down)