My favorite square is the Marktplatz and the Schloßplatz, which almost merge into one another. In the middle are the town hall and the market church. I particularly like this square because there is a market there twice a week and you can get lots of different things there. Fruit, vegetables and flowers, of course, but you can also eat delicious sausages and have a drink, perhaps a glass of wine or sparkling wine.

It's very interesting and you see a lot of people. There are beautiful historic buildings around this square, which is very illustrative of the historicism for which Wiesbaden is known. There are lots of benches there; when the weather is nice you can sit in the sun. There is also a very good ice cream parlor where you can get a large selection of ice cream.
Even when there is no market, it is a great place to pass the time. There are lots of nice places to eat around the market, for example the Lumen, where you can find the old market column, which is also very nice to look at, or the Ratskeller Andechser in the town hall, where you can enjoy a good home-style meal.

The market square is also the starting point for the Thermine, the little train with which you can comfortably discover Wiesbaden, as well as the tourist information office. There you can get lots of useful information and suggestions and you can also pick up a city map.

Perhaps this will also become your favorite place.