First of all there is the difference in size. Mexico City is humungous with a metropolitan population of well over twenty million people. It is the largest city in the Western Hemisphere, and the seventh largest city in the world. Madrid, on the other hand, has a metropolitan population of around 6.4 million. It is this difference that defines many of the pros and cons between the two cities. Obviously, managing a city the size of Mexico City and dealing with the problems of urban life are a gargantuan task. The criticisms that I make about Mexico City, do not mean that I do not love it, but are a reflection of its monstrous size.
SAFETY - Although Mexico City may seem more intimidating, I have never felt unsafe in either city. Many people, mostly people who have never been there, think that Mexico City is a dangerous place. In fact, for a visitor, it is probably no more dangerous than any other big city. Obviously, as in any metropolis, there are areas where one should not venture, (although I have explored some mildly dicey neighborhoods during the daytime with no problems). I do take common sense precautions especially in crowded areas. I don't carry a lot of money on me, and usually don't carry my credit cards if I am not going to use them. In places such as the "metro" (subway), my wallet goes immediately into my front pocket.
Madrid is considered a very safe city. There is very little violent crime, although it does have a reputation for having a lot of pickpockets. Fortunately (knock on wood), I have never had a problem. I take the same precautions that I take in Mexico City. The people of Madrid are famous as "gatos" (cats) who love to go out to the restaurants, bars, and clubs until the wee hours of the morning. Comparing the two cities, I might give a slight edge to Madrid in this category, only because the downtown streets are so lively and seem so safe late at night.
TRAFFIC AND PUBLIC TRANSPORTATION - Madrid wins hands down in this respect, and this is the one aspect that I most dislike about Mexico City.
Traffic in Mexico City is utter chaos, and it can easily take a couple hours to travel by car across the city. There have been numerous times in the car with my friend Alejandro that I wanted to jump out of my skin. There is no way that I would drive there! Madrid certainly has plenty of traffic, but it seems to flow more smoothly and the drivers are less crazy. Also, Madrid (at least the areas that a visitor would want to see) is more compact and more easily seen on foot.
Both cities have excellent public transportation systems. However, because of Mexico City's sheer size, its subway and busses are often crammed like sardine cans. I have never felt claustrophobic on Madrid's subway or worried that I would be able to push through the crowd to get off at my stop.
CULTURE - Both cities are the cultural centers of their respective countries, and are cultural hubs for the entire Spanish-speaking world. In both you will find great museums, theaters, concert halls, and historical sites.
In this category I would have to give the edge to Mexico City. Madrid is famed for its art museums... most notably El Prado... but Mexico City is said to have more museums than any other city in the world. In my opinion, what gives Mexico City the edge is the vibrant fusion of Spanish and indigenous cultures. In the heart of the city you can see a massive, baroque cathedral, and next to it the archaeological remains of the Aztec temple.
FOOD - I like Spanish food... especially the "tapas"... but I LOVE Mexican food, and in Mexico City you can sample all the regional variations of Mexican culinary arts. If you should tire of Mexican food there is an abundance of restaurants serving cuisines from all over the world. Mexico City wins without a doubt!
PRICES - I find Madrid to be less expensive than its rival Barcelona, and I am sure that with the decline of the euro the prices will be more reasonable. But Mexico has always been a bargain for travelers... and with the current rate of exchange it is an even bigger bargain. Sure, Mexico City is more expensive than most smaller cities in the country, and of course you can pay a princely sum at the ultra-ritzy hotels and restaurants. But I doubt if there are many major world capitals that you can visit as economically as Mexico City.
WEATHER - In spite of its tropical location, Mexico City's altitude moderates the temperatures. It is never extremely hot. In the winter it may get a tad chilly at night, but mid-day temperatures of around 70 degrees are much more attractive than the snow and cold of Ohio. Winter is the dry season, and summer is the rainy season. It used to be that in the summer the days would be sunny, and in the late afternoon there would be a rain shower. However, in recent years it seems that Mexico City is getting above average rainfall. The last time that I was there in the summer, I saw more clouds than sun, and there were several torrential downpours.
Madrid is extremely hot (and dry) in the summer. In the winter it can be cold and occasionally even snow a bit. I find that September is usually a very good time to travel to Spain. The weather is still summery but not as uncomfortably hot as in July or August.
Mexico City wins in the weather category.
POLLUTION AND CLEANLINESS - Mexico City used to be considered the most polluted city in the world. It has improved its air quality in recent years, but pollution is still a problem... especially during the dry season. I'm sure that Madrid has pollution, but it is not nearly as obvious. In fact, the skies of Madrid seem to have a very beautiful, transparent quality.
One thing I don't like about Madrid is the amount of graffiti on the neighborhood buildings. But the Spanish capital is generally cleaner than Mexico City (well, except perhaps on weekend mornings, when it is obvious that the Madrid "gatos" have been out partying all night). Let's face it... it's hard to keep clean a city of over 20 million people. Mexico City makes a valiant effort. City workers are constantly sweeping with their brooms made of twigs, and shopkeepers are washing down their sidewalks in the morning. But even in more upscale neighborhoods, the trash bins in the parks are frequently overflowing with refuse.
Madrid wins this one.
ATTRACTIVENESS - Madrid has never been considered one of the beauty spots of Europe when compared to cities such as Paris. Nevertheless I find central Madrid to be very attractive. (The outlying districts with rows of boring apartment blocks are a different story.) I love to wander the narrow streets of old Madrid. The city has more parks than any other city in Europe. Much of the architecture is stunning.
In Mexico City... there are huge swathes that are downright ugly, and could serve as the setting for a tale of a post-apocalyptic world gone haywire. Many buildings, even those that are of recent construction, look dilapidated and sorely in need of maintenance. And yet in this huge metropolis there is so much that is beautiful. The heart of the city is filled with more colonial churches and palaces than anywhere else in the Americas. Many of the old buildings are crumbling, but a good deal of the historic center has also been spiffed up. There are neighborhoods such as Coyoacán and San Angel that are delightfully picturesque and seem light years from the big city. There are districts such as Condesa that have a European vibe. The city's main boulevard, el Paseo de la Reforma, is lined with ultra-modern architecture.
It's a hard decision to make, but I will call Madrid the winner in this category. However, it's not really a fair decision because I am not familiar with that city's less desirable neighborhoods. And if you were able to create a city comprised of all the lovely sections of the Mexican capital, I suspect that it would be larger than Madrid.
I could write more, but I have rambled on far too long. So which city do I prefer? I love them both for different reasons. Mexico City is chaotic... that is perhaps a part of its appeal. But after a while it can also be an exhausting city. So if I had to choose between the two as a place to live, I guess I would go with Madrid.