As far as value for your money, amenities and location, you probably won't find a better hostel in Berlin than Singer 109. I stayed here for 8 nights. They have good wifi, but it started lagging toward the end of my stay. They offer laundry service (wash/ dry/ detergent) for only 5 euros, which is pretty cheap. My room was the standard dormitory style with 6 bunk beds, 6 lockers, a television (which wasn't plugged in), a desk w/ 2 chairs, and a huge window with heavy curtains for those that party till early morning and sleep till late afternoon. There's also heaters in the rooms that can be controlled by the guests, which was great because it's getting pretty cold in Berlin. The hostel has a nice little common area for lounging or taking your laptop to get some work done if you don't want to stay in your room. They also have several computers available for guests to use equipped with internet (I didn't use them, so not sure if there's a charge for them). There's a breakfast that ends at 11am that only costs 5 euros.
My only issues were that there were no irons or hair dryers in the suites. Also, the hostel is co-ed. For most of the week, there were only guys in my suite. But during the weekend, there were two women that checked into my suite. It was a bit weird because I found myself more careful about things like...not coming back into the suite after a shower in just a towel. I sensed that a few other guys were a bit more cautious too.