Schluter bullnose works great if there is no bullnose made to match your tile. Much better than showing a raw edge. But if there IS bullnose for your tile, it makes for a much smoother flow, not adding another material into the mix. As for which will last longer, both, if installed properly, will outlast you OR me. As for pros or cons, beauty is in the eyes of the beholder, that being the homeowner. :-) In other words, which every YOU like better, in spite of my long winded speech. LOL

I'm not a pro, but I've used that same Schluter decorative profile to trim around a shower niche before. When I cut the trim per Schluter's instructions, I initially ended up with a rough edge as well. I then took the time to gently sand the edge until it was crisp and smooth. (I had to cut the trim piece a little long in order to do this.) It was tedious, but I meticulously cut and sanded the pieces until I had a nice snug fit. It looks like your contractor did not put in this effort. Picture #3 looks especially egregious. While I think it will look better once grouted, I wouldn't be very pleased with this either. I believe this is the Schluter data sheet for these profiles. (Feel free to google Schluter RONDEC-DB to navigate there if you're not comfortable clicking the link. The data sheets are PDFs near the bottom.) Regarding finishes, it reads: "The profile is available in stainless steel, solid brass, chrome-plated solid brass, anodized aluminum, color-coated aluminum, textured color-coated aluminum and PVC. RONDEC’s wide range of materials, colors, and surface finishes allows for color coordination with tile and grout and the creation of interesting accents in decorative designs." That tells me that your contractor could have selected a color coated option to coordinate with your tiles if he'd asked you what you wanted and put in the effort to order it. I'm pretty sure I used the stainless steel option, but that's what I wanted. It also was available at a local store. If I wanted something specific, I would have had to order it in. I wonder if you contractor didn't want to put in that effort to order it.

Seeing you have a contractor the detail that you are inquiring about should not be your concern. It is the responsibility of the contractor to have the knowledge to determine appropriate components. If you make these decisions then you have taken on the risk of a improper selection and are now responsible for the final result. Don't like the way it looks. Now it's on you to pay to replace. Turns out not to work. You pay for new material and delays on your project. If your contractor can't make this decision stop immediately and get another contractor. Your only decision should be which finish you prefer on the profile edge.

why not just do the bullnose? And perhaps go w/a 4x12 instead of a 3x6. here's my shower. I used a 4x12 with bullnose on both the vertical, for outside edges, and horizontal, for the top row the bullnose option is one of the cleanest looks you'll get the schluter I did for the accent and the niche (I chose black) close up of that same 4x12 tile but in a diff layout. (this is my neighbors shower) we opted for a stacked pattern layout. slightly more modern looking this one got the Schluter edging on the outside In this one, the tile didn't come w/a bullnose edge. we went w/the pencil liner. again, a larger tile (either a 3x12 or 4x12) and a stacked layout does this give you a better of idea of what look you like?