This is primarily a shop for macarons (which are delicious btw) but they sell Mariage Freres tea and have a decent selection to choose from. At the counter there are little jars so you can smell their selections of teas and order a cup to try before purchasing. The gentleman who helped me knew the teas well and was able to show me ones I liked given my preferences.
The people who work here are very helpful without being annoying. They are great at making recommendations if you give them your taste preferences.