I am not sure based on what are criteria, you are marking some exchanges small or big because I do see some exchanges are not having big volume yet they are listing wide range of coins and tokens and in big numbers too. I assume by popularity you are classifying small exchanges from rest of exchanges. Because, when an exchange becomes popular, it will become big too in terms of reputation and volume.

I used tidex and I guess they are not grabbing big attention from this community but my withdrawal requests were processed on time. Mercatox is another exchange I am following but not yet trading there. When I need to sell some new tokens then I look for new exchanges hence I do not need to look for more exchanges frequently.