I'm no massive history buff as pretext, I just like medieval weapons.
Despite that, there are many stories of great warriors passed down in many cultures. I know the names of people like Ragnar the Red, Sigurd, William Wallace, Miyamoto Musashi, Oda Nobunaga, and I'm not from any of those cultures. In some cases known for leadership, but in many cases specifically for their martial and duelling prowess. These people have armour in museums, their names permeate current culture and media (characters for example being named Hanzo in videogames, referencing Hanzo Hattori, Braveheart about William Wallace e.t.c.). Why are there no stories passed down of champions in the European tournament circuits? The only figures I hear of from medieval England are monarchs and a few lords or barons, and this is never in the context of their individual battle prowess. Considering that Knights trained their whole lives to be warriors just like samurai, why do regular people not know their names? The only stories like that I can think of from England, are the Arthurian legend and St George, then maybe Joan of Arc from wider Europe.
I'm a little biased here due to my flair, but I'm a little surprised to see this question asked specifically about England. In English-language media (for obvious reasons) and culture at large, I would say medieval English figures are vastly over-represented. In most modern Robin Hood adaptations, Richard I is portrayed as the masculine, heroic, good king to a simpering and cowardly Prince John, in large part because of Richard's reputation as Richard the Lionheart, named for his reputation as a soldier and a knight. Likewise, Henry V and Richard III, just to name a couple, have been immortalized in two of Shakespeare's most famous plays, where they are portrayed as skilled and brave soldiers. For non-monarchs, William the Marshal is also a very well-known figure, a legendary contemporary of Richard and John who is said to have unhorsed Richard I at a tournament. Although he's not as well known as the kings, he has been the subject of many books (both scholarly and pop historical) and has a whole wikipedia page about his depictions in pop culture.
I would venture to guess on the whole that more people on the street in the US or UK have heard of Richard the Lionheart or Henry V than know who Oda Nobunaga or Ragnar Lodbrok are. Out of your list of examples, two (Ragnar and Sigurd) are mythological figures, not historical personages who fought in real wars. To my knowledge no one from the list you mentioned, with the exception of Oda Nobunaga, would have armor or indeed any artifacts in museums at all. Nobunaga lived in the mid to late 16th century, a period for which we have far more surviving artifacts (especially armor) than we do from the 1100s. Two of these figures, as mentioned previously, are fictional. William Wallace, although well known due to pop history and Braveheart, was not all that important in his own time, and not all that successful of a soldier on the whole. He won one battle, lost another, and was then captured and executed. He was probably a fairly good combatant, as experienced medieval soldiers tended to be, but I don't think there's any substantial evidence to support a thesis that Wallace was well known for his personal skill at arms as opposed to his (far more important) ability to command.