My chestnut has Havana with a white numnah.TBH I think all tack should be brown, bit old school that way. Although my bay has black, daughter's choice.
FDC
I have a chestnut and was brown tack all the way...
Until the only new saddle that fitted him was black!
I now have all black tack and on his colour I prefer it. Black tack comes up very shiney when clean and it looks very smart.
Also it's incredibly easy to match black tack. When I was using brown/havannah tack it could be quite hard to match my saddle, bridle, reins, martingale, girth ect to exactly the same colour. Unless I used exactly the same brand (not really practical when my saddle was black country and bridle Jeffries!) then I did notice that different parts of his tack was different shades of brown!!
I do like brown tack and I have kept everything just in case but my chestnut (sort of a dark golden chestnut with a liver chestnut mane) looks much better in black.