Alex, To make money in photography, there are many variables that you want to maximize. Which variable you maximize the most is determined by what you intend to shoot and how you make your money (and vice versa). The variables transcend just photography and include such things as time efficiency, technical accuracy, novelty, composition, reliability, cost efficiency, ease of use, prestige, originality, cleverness, and perhaps longevity (and many others of course). With the rise of cheap, efficient, reliable, and accurate digital photography for the masses, the variables that set the pro apart from the masses gets narrowed somewhat.
On the one hand, the AF lenses are terrifically reliable in nailing focus and therefore are extremely time efficient and hence cost efficient. If you are doing a wedding, or you have many projects on your plate at competitive pricing, then you need a reliable, cost efficient camera and lens, period, end of discussion.
On the other hand, if you want to distinguish yourself at the margin, meaning the last 2% of wowness, then I think in many circumstances the German bred lenses take the prize home. The exceptions of course would be the wow factor involved in action photos, where there is really no way a Leica or Zeiss could compete, almost by definition. And I think the Nikons and Canons of the world have a lock on lenses above 200mm, with rare, very expensive exceptions (like Leica 280 f/4 APO perhaps). But apart from that, the novelty look and extreme resolutions of the German lenses are more likely to set you apart from the masses if you are a patient soul. I simply think that assuming you can make the capture happen, your ZE shots will have great longevity (meaning, "oh, that's a real keeper shot for my grandkids"). When I take a photo with the 21 ZE, I get comments from various folks who have no idea it's a Zeiss picture, but do know there's something special about the photo. That's why people use Zeiss lenses. In truth, some of it is just the novelty of the look; if everyone could afford the Zeiss, then the photos would be more pedestrian (however still retaining superior aspects nevertheless).
Bottom line. I have many top Canon AF lenses, and the 70-200 2.8 II is without doubt the most sophisticated lens I've yet seen. It is an amazing lens, and if I want to guarantee capture after capture, I reach for it, or my 24-105, or my ..., but if I don't need capture after capture of reliable shots, I reach for my Leica 180 APO for hiking/nature trips and slowed down photography, particularly landscape type photography. Apart from action shots, slowed down photography is where the true all time keepers are found, IMHO. I personally like the Wide German lenses and long Canon lenses, with the split being above 100mm (give the nod to the Zeiss 100 ZE or the Leica 100 APO or Contax N 100 near the split).
It all depends where you want to draw the line. Personally, I wish I had the patience for large format photography, but I don't. I know I wouldn't get many captures simply because it's too burdensome to set up. For me, the Zeiss is just burdensome enough that most folks will avoid it, meaning my photos will stand out relative to theirs. It's a definite barrier to entry which sets the MF photos apart at the margin. I will grant that many folks will never pick up on the difference in the photos, however. It is definitely "at the margin".