I still remember my first experience entering this place. I was disoriented and jet-lagged, expecting something like the run-down dirty subway system I had gotten used to in New York, but when I entered the station and came up to the escalator that extended down as far as the eye could see, I instantly realized that this was something different. The best way I could describe it would be like this: imagine if every single station was a mix between a museum and work of art. Chandeliers hang from the ceiling, and, depending on the station, tiled murals could be on the walls depicting events from the country's history or statues could line the whole walkway. Every single one is different and has features unique in and unto itself. For example, the station Belaruskaya depicts images related to Belarussian culture, Dostoevskaya has a giant image of Dostoevsky's face. You'll find something new wherever you go and it's always interesting.
There is one commonality, though, that every station has. No garbage can be found anywhere. There is almost always someone cleaning and the stations are completely spotless. Plus the trains always arrive within two minutes or less from the time the previous one departed, no matter what day or time it happens to be (unless it's between 1:00am and 5:00am since the metro doesn't run then). Anyway, between the decor, efficiency and cleanliness, I've never seen anything that compares to Moscow's metro, and therefore it easily takes the top spot.
I'll start by admitting that before I arrived, I wasn't even sure if the city of Kazan had a metro. Turns out (as you can guess by this post) it does. And despite there being only two lines, it is one of the coolest, most creative one's I've ever encountered. Every single station is decorated with huge murals depicting different events from Tatar folklore or history, each with a different theme. Even though I'm not the foremost expert on the topic, it was so fascinating to get such a glimpse into a culture that I know very little about, which was made all the more exciting by how intricate and detailed every image was. Also, like Moscow and pretty much every other Russian metro I've ever been on, it was unbelievably clean. I just can't give it the top spot since I had to wait over ten minutes for the train to arrive on multiple occasions.
Inside the station, Almaty was actually pretty similar to Kazan with regards to decoration related to culture and history. Likewise, it was extremely clean, only cost 80 tenge (25 cents) to ride, and probably had the most modernized train cars I've ever ridden on. The only downsides though were that there was only one line, thus rendering a good deal of the city inaccessible, and ten minute gaps between trains. For that it falls short to Moscow's vast network of highly efficient lines, but remains one of my all time favorite metros.
Don't get me wrong, I really like Boston as a city, but its metro system 'The T' sucks. You can go faster on a bicycle with two flat tires. It may sound like I'm joking, but while riding The T, I have actually been passed by several cyclists (which is possible since The T is above ground). Whoever had the "brilliant" idea of designing it decided to intersperse the metro system with normal roads and traffic, so as a result, the trains often have to stop for cars, pedestrians, and whatever else happens to be roaming the streets of Boston. And none of this is helped by the fact that there is no rhyme or reason to the metro's layout, which looks like a deformed web constructed by a drunken spider.