(1a). Personally, I also like (1a) best, with (3f) being a close second, but there are two reasons I am not yet happy with (1a):
2) Some people feel it looks evil because of the strong "eyebrows" (which are actually part of the animal's skull). It does not look evil to me, but it will give this impression to some people. It's not really a problem, but one has to be aware of it.
1) It does not yet look like a gnu; it rather looks like a bull. This is the best photo of a living gnu I have seen so far (thanks to josX for the link): http://aminet.net/aminet/dirs/aminet/pix/fauna/safari08.jpg
I am not yet happy with (1f) because the gnu looks a bit too old.
Therefore, I created two more variations of a gnu with eyes (images (1b) and (1c)), trying to combine (1a) and (3f), and the photo of a live gnu:
http://agnes.dida.physik.uni-essen.de/~anja/gnu/lineart/
Also, the pictures are now links to slighty larger versions. The graphics has to look interesting in t-shirt size, not in web button size, so the larger version is somehow more important then the small version. One can do a lot with the eyes. So far, I like (1c) best; this gnu certainly does not look evil. What do you think? Is it too cute now?
Just for sake of completeness:
I am using xfig and / or sketch with and without autotrace (with and without pstoedit). Each has have some advantages and disadvantages. I can tell you afterwards which of them I used mostly.
The server apparently does not exist any more; I don't know where the project moved. If anyone wants a copy of autotrace I can mail it (the tarball has 120kB, the documentation 65kB, and it's GPL-ed).
Best wishes,
Anja