Which GPS is best for Mexico?

I actually do not own one yet, but the garmin that has mexico maps in it, then you can purchase another mexico maps for it which as the backroads and very useful if you plan to get off the beaten track at all.
Hopefully someone who has one will correct me if I am wrong on this.
I am looking to purchase the one to put into my RV,in my toad, on my motorcycle and on the quad which has the 7" screen I think.