Derby vs loafers

[Requin]

Definitely. Dark brown suede loafers with flannels look great. Even better than those black ones would.

Dark brown suede loafers is a 'cheat code'. It just goes well with almost anything, within the confines of tailoring.
On that note, I only found out recently that dark brown loafers go very well with charcoal flannel trousers.

I have a contrasting appearance type, known as deep winter in color theory. This means that light and warm colors greatly worsen my appearance. Because of this, my wardrobe only includes dark gray, dark blue, burgundy, and dark green colors. If I buy dark brown loafers, they will have nothing to match. I think the color of the shoes should find some response in the rest of the image, but I do not have any other dark brown things. For example, in the summer I wear a dark blue linen suit. Under the jacket there is a white T-shirt. I think it is much more appropriate to wear blue suede sneakers in this image than dark brown loafers, which will stand out from the general color scheme.
Since my wardrobe is dominated by grey and blue shades, I choose black shoes.

 

[Shanghaining]

Loafers tends to be discovered by many who already have had quite a few pairs of Oxfords and Derbies to start with, particularly during the earlier years of their life and career, but eventually some will find tying, waxing and replacing the laces a bit cumbersome, then they would experiment with the Loafers and embrace the simplicity of just slipping them on and off.

Although it is in the middle of Winter hovering around zero degree Celsius in my neck of the woods, I just rotate between my burgundy Shell Cordovan and dark brown Loafers most of the time (and reserving the unlined Whisky Shell pair when Spring and Summer arrives), paired with heavier wool trousers, sweaters and jackets, adding on a Cohérence trench coat if necessary.

Loafers also tend to reduce the perception especially with tailored clothing of that just came out from the office look, so it creates more of casual disguise to blend in with the crowd. Even so, a good pair in black could still complement well with formal suiting, across fabric shades and body shapes, although Mr Blankfein did need to resole his pair.