Alexandrplatz is not known for gastronomy, mostly restaurants and cafes are very average here. Kantine Deluxe stands out. It's a great spot for lunch - a'la carte there is a set of courses that are always here, and every day there are new specials which makes a great assortment. You can come every day. Some of the courses are a bit too rude and fast-foody, hoverer general quality is very high
You need to order at a counter and then pick up your food, still, there is a table service, which is friendly and multi-lingual. Rush hours are not perfectly planned tho, you might wait
Atmosphere is somewhere between fast food and a cafe, you see how your food is cooked, and you can chill a bit while waiting. Special credits for the summer terrace
Tables are always clean, that's the general impression for the whole KD.
It's a great place to have lunch
If consider that you need to order and pick up food at the counter - a bit expensive, still for Alexanderplatz fair price. Lunch 8-12€