I think some images look best when converted to B&W or sepia tone, or have some type of filter or "look" applied to them. Some images can easily be processed to have different looks applied to them. I use the term look because Kodak's early professional software called them "looks". For example, if you add a fairly coarse, irregular, somewhat large grain pattern to an image that has been converted to B&W, and it has a very long tonal scale with good highlight detail, that could be called a Tri-X Pan B&W "look". Sometimes a faded-color look with negative clarity looks soft,effeminate, delicate...which is at the opposite end of the spectrum of full-color, super-vibrant, hyper-clarity image processing like the masses love on 500px.
The issue is though, if you do each image wildly differently from every other one, then you're not offering a set of images, but a collection of singles...
I think it's good to process an entire session in what I call "realistic color", and then to offer some different looks in a limited palette, but spanning the entire set. Like for example, you have the entire set of 20 done in realistic color, but then have six of the very best poses offered as vintage color images, which look pretty much the same across the subset of six.
But hey...you can offer whatever you really like. I don't think that there is a single right answer on this. There's room for interpretation of photos, and like I said, you will find that some images really might look much better as B&W or sepia-toned images, or with fairly extensive processing that moves them away from the realm of realistic color; I think today, more than at any time prior to this time in history, people are actually ENJOYING seeing different types of filter effects and different "looks" to their images.
