Best place to exchange for Pesos

Where’s the best place to exchange US dollars for Pesos? Best exchange rate?

Get them from an Banamex ATM, at the SuperNorte grocery store across from Sam's club gave me 20.1 -1 on Sat.
ATM Fee was 30 pesos.
I used a no fee foreign transaction debit card from Capitol One.
There are other US banks that do the same, Bank America does from their Mexico partner banks. I've read.
If you are going to actually exchange $$ for pesos the Electra store had some good exchange rates last time there.

I asked at Chase Bank here today and they are selling at 18.89 to 1. No fee.

You can do almost as well by checking out a few of the local exchanges on the street. the first on into town across from sams has had fair rates. cash and carry no fees, no muss no fuss.