I have been living in Mexico since 2004.
Millions of people move to Mexico to enjoy life more.
Where I live there are people from Argentina, France, Belgium, Germany, Canada, The USA, Switzerland, Chile, etc.
If you are looking for a city, Morelia is a good choice.
See: What’s the best city to live in Mexico over the winter?
Brian Fey’s answer to Where is Michoacan, Mexico?
Notice the nice stable high temperatures. In a well built house here you should not have to spend any energy to heat it or cool it. The summer rains cool things down just when they would get too hot.
The nights do get chilly in the winter, but that makes it so there are no nasty bugs to deal with.
I prefer the highlands over the coast since the coast can be too hot much of the year. I will not live in a humid sweaty place. I usually spend a month on the coast where housing costs little if you rent by the month. Plenty of expats live in beach places, it just isn’t for me.
Rents generally are cheap depending on what you want to get and where. Extremely cheap options are available. I know one guy who paid USD $30/month for a simple house in a rural town. You might want to budget more though. Many expats seek housesitters and a person who is responsible and has a good reputation could live for free all year in very swanky places.
A six month visa is easy for people from most countries to get, and getting longer term visas are quite easy.
Public transportation is excellent; far better than most places in the United States.
If you are from the US, then you will find it easy to return there when you like by land or air. And your friends can visit. Despite the news, it is quite safe and there are millions of expats from other countries. Some areas have concentrations of expats: Ajijic, San Miguel de Allende, and Patzcauro. And there are plenty of other places as well. I prefer the Patzcuaro area since I don’t want to live in a gringo enclave.
Here is more informaton about the cost of living in the Patzcuaro area.
Mexicans are friendly overall. Some speak English and have worked in the States. If loud noises and parties bother you then you should choose your housing to avoid that. Spanish is fairly easy to learn and no one will mind if you don’t speak it well.
The food can be excellent. Street food is cheap and tasty. A healthier option would be buying fruits and vegetables straight from the markets. Fish and other seafood is very cheap.