Or strictly speaking, words with the most heterographs, i.e. groups of words that are pronounced the same but have different spellings and meanings. There is this set of four:
new
knew
gnu
nu (Greek letter)
all of which (in some common dialects of English) are pronounced “noo” (in other dialects some or all of them are pronounced “nyoo”).
The most I know of is “air”, though some of them are a bit of a stretch:
Air: Breathable gas
Err: Make a mistake
Heir: Scion
Aire: A tune (as in, “Londonderry Aire”)
Are: A unit of area equal to 100 square meters (it’s what a hectare is 100 of).
There’s also bite, bight, and byte, and it seems to me I used to know another one for that set, but I can’t remember it.
EDIT: Another foursome.
You: Second person
Ewe: Female sheep
Yew: Bow-wood tree
U: 21st letter
Nice, although I don’t recognise “aire”. I thought the tune was called “Londonderry Air”. Still, with “ere” that’s a set of five. I don’t pronounce “err” like “air” myself, but I think I have heard others do so.
And of course, French has a set of 6 homophones (though only five different spellings) that are, AFAIK etymologically distinct: vert (green), ver (worm), vers (verse), vers (towards), verre (glass), and vaire (a kind of fur, weasel I think). And Cinderella’s “glass slipper” (makes no sense) was based on confusion between the last two words.
Cerf was part of the Harvard Lampoon in its glory days, and while there published a cartoon piece with Michael K. Frith and Jack Winter called “See the Merino Standing There, with His Long, Shaggy Hair.” A merino is a type of long-haired sheep. Each page is a cartoon of a merino plus a caption of wordplay. You see the merino with a long shaggy:
hair
hare
Eyre
Eire
air
hayer
heir
before veering off into “C,” the merino or the merino “Stan Ding.” The cartoons are great and you can’t get the humor without them. So you have to buy the book. You will thank me.