I'd prefer to live in medieval times, but all depends on country, century, and social class. The medieval times were indeed very prosperous, rich and rather peaceful. For example -- Bohemia didn't have wars between 1300 and 1396, which was the second largest peace an our history.
In medieval times I'd need to pay only 10% tax. I'd never work on Sundays and have numerous holidays, near to 100 in a year. While many people think that the medieval era was dirty, Romans and Goths were cleaner that 19th century citizens. It was normal to bath in medieval times and there were a lot of bathhouses.
The life in medieval system was also based on classes, which were also movable, so I think it's better to live at that time as feudal landlords and peasant, 'cause there are a lot of opportunities to change social status.
Also, there are some other reasons why I'd prefer to live in medieval times than in modern world. At first, I could live in castles, towers, manors. I could own as many swords and other cold weapons, and nobody would shock on this fact. And of course, the life entertainment was great: duels, jousting, archery contests, bards and jesters.
But above all, my hobby is sword fighting and that is the main reason why I want to live in medieval time.