I expect that in the long run, if I took the time to understand every aspect of slic3r and tweak all the parameters just right, I might be able to get the same quality as S3D Creator just did for me. The difference is that Creator seems to know what's right to use in every situation that I've thrown at it (which is admittedly limited to what I was working on today).
Here are my problems with slic3r, and please advise me if I have been missing something obvious. But I have not seen much difference between slic3r versions 0.9.8, 1.0.0, and 1.1.0.
(1) Slic3r does a huge amount of retraction. I would guess this is a quality of the algorithm issue---per layer, slic3r can only get the number of paths needed down to a number that's usually in the dozens. S3D appears to get the number of paths down to one or two.
(2) Slic3r generates a huge number of tiny segments that are so small that they cannot possibly make any difference to the print, but because they are separated from the other segments in the layer by a retraction, they tend to cause excessive amounts of blobs and stringing.
Every time slic3r does a retraction, it increases the chance that pulling up the extruder will cause the layer to pull up with it, which increases the chance of layer delamination, and ultimately print failure.
(3) Recently I have tried making rafts in slic3r, and what I get does not look like a raft at all; it just drops down some short lengths of crosshatch lines randomly here and there, sometimes under the print, sometimes not. I did a raft in Creator and it made a solid surface under the whole print. I could choose how dense to make that layer, how many vertical layers to make the raft, etc. I could not get anything like that in slic3r.
(4) I tried generating support structures in slic3r, and they were so close to the walls of the printed part that it was all stuck together, and I couldn't get the support structures off of the piece after it was printed. I looked for some parameter that would let me pull the supports back from the walls of the piece, but I could find no such parameter.
Today I got a complete epic fail in slic3r, where it printed the first layer at 0.1mm and the second layer at 0.675mm (not good!). While this was admittedly my fault (I had two separate structures that were accidentally intersecting, making a non-manifold object), slic3r 1.0.0 just sliced it (wrong) with no comment. At least slic3r version 0.9.8 had the good sense to warn me that I had a non-manifold object.
Sorry this is getting off-topic. I should start another thread on slic3r problems. We are supposed to be admiring a translucent whale here!