William Ruled by conquest. Effectively, do as I say or I kill you. Harold still had to depend on the authority of his election and on the support of his nobility.
Harold seems to have been a competent ruler who did quite well in battle. He might have been a competent king.
Harold winning at Hastings means that there is no foreign king who has to waste inordinate amounts of wealth building castles to secure his rule. Not that castles won't get built, but there will be less of them.
No wars with France means all that money won't be blown that way.
essentially, the Conquest of William means the history of England is moved backward 200 years and a lot of wealth gets blown. The nobles re establish their authority at Runnymead, and the dance goes on as usual, with England being poorer for it.
Harold wins, there is pretty much the same constitution as in in 1250. Lots of names get changed, england is wealthier, less prone to civil war, but gradually takes over all the islands and is a whole lot more prepared to take advantage when some Italian cons the Spanish into letting him find a route to china by Sailing west.
I can even see where England would do the same things the Tudors did in the ATL. I can see the ATL king being in need of cash and closing down the monasteries to get it, and doing an England only reformation.
And I can also see where a series of English kings give up more and more authority to the towns in order to counter balance the authority of the lords.
With 200 years more wealth and whatever, the English might have followed the path of the danes and made settlements in North America in the 1400s if the science kept up the good pace. And with that much more wealth, they quite well would have.