Here in South
Africa, peg rhymes with leg and beg. Short e, as in bet. I am familiar with leg rhyming with plague, but only as a dialectal (UK) pronunciation which some of my elderly relatives used for comic purposes "Ee, me lague" when complaining about, say, stiffness or a sudden cramp.
We have two different
Megan situations here.
Megan usually has the peg rhyme and
Meagan is always MEEgan, long e as in speed. I've never heard MAYgan, but that proves nothing of course. And some
Megan people use the MEEgan pronunciation.
The only
Tegan I've met pronounced it TEEgan; for what it's worth, she was British.