I say it the Spanish way: "meh-reng-geh". I've just always been used to it, from talking about the music genre. lol.
If it was spelled "Meringue", I'd say it like "muh-rang".
I've always pronounced it 'murr-ang' because... that's just how I've always pronounced it and heard it pronounced. I didn't even know a Spanish pronunciation existed until now. I'm going to have to use it now!