At the time of the visit, there was the most profitable course near the hotel. I've been there three times, and I've never stood in line, even though there are a lot of people. They work smartly.
Easy to find.
For Istiklal, the course is consistently good. I've only seen a better course in this part of the city right next to the bridge. They did not ask for a passport, they did not take a commission. However, as in other exchangers.