Probably none of the above..................I have been going south for over 20+ years and the only large icties that might have them are Ensenada, Loreto, La Paz and Cabo. However, check with the local banks in the smaller cites and you just might get lucky. Remember that when going to an ATM you are going to be charged a fee that might be unknown to you, plus when you get the money your bank is charging you at a current market rate for the peso, but it might not be the day that you bought the cash............It is a crap shoot for the exchange rate.
Try carrying US money and changing it at banks or money exchanges which might be a better place to check about ATMs. I have found that having Pesos is usually better for at least buying gas since each town and gas station even though PEMEX have different exchage rates. Take a calculator with you and always ask what the combia (exchange) rate is for dollars versus pesos. Plus check that the gas station attendant always zeros the pump before putting gas in you vehicle and you see it.
Hope that helps you out and gives you some food for thought.