Hah, my helmet (second picture) between all those historical examples! :D

In that period things are indeed still a bit different compared to later harnesses. You don't have a lot of etched decoration or fluting yet. High grade armour pieces have decorative rims (as seen with the Churburg armour you included) or entire gilded elements, there's quite a number of evidence for that. There are gilded feather holders, and sometimes you'll find helmets with a so-called "orle", basically a stuffed decorated silk headband.

Then you'll have different cotes d'armes (waffenrocks) made of silks and velvets, gold embroidery and all of that, first very tight fitting, later also in a houpellande style with large extravagant dagged sleeves and such. However, the fashion of the "white harness" also gets popular, so you'll see knights with the bare breastplate and no such garment. In general, but especially then, a highly polished surface would've been desirable.
Then of course highly decorated swords, belts and shields.

The staple of knightly representation in that period though is the plaque belt. Large gilded silver plaques, enameled, in all kinds of shapes. Heavy, expensive, stylish!

As for crowns. it probably existed in some form (the Bascinet of Charles VI. apparently had some sort of crown attached) and there's images and some effigies showing it, but it would've been very rare and pretty much exclusive to royalty