I personally went with the 180. A 6ft. tank is a lot to manage and definitely gives ample room for its inhabitants. I didn't want to have to get on a step stool to reach the bottom either.
Another reason why I chose the 180 over the 210 is because they both use the same stand. So I rather have a tank on the stand that isn't pushing the limits of the stand. Obviously if you build your own stand it doesn't apply. But I've seen commercial stands fall apart from water damage. So I got the high-end stand for my tank, not the standard stand, because it's a much better built stand and much nicer as well.
Another reason why I chose the 180 over the 210 is because they both use the same stand. So I rather have a tank on the stand that isn't pushing the limits of the stand. Obviously if you build your own stand it doesn't apply. But I've seen commercial stands fall apart from water damage. So I got the high-end stand for my tank, not the standard stand, because it's a much better built stand and much nicer as well.