i'll go straight to the point, gla is cheaper than ada but it seems the glass is just a bit greener than the ada's but it's not like it'll affect how you see the fish or tank so you'll save a bit there. do aqua has some nice stuff at the adgshop.com it's pretty much ada just cheaper version of the ada brand. Also gla has a sale going on now on their nano tanks so best to take advantage of it while it lasts. l got a 48g rimless from them and no complaints till this day.
here is the website
here is the ada site
if you want to know how many gallons the tank holds click tech specs and then it should tell you. the do aqua section is right below the ada section and it tells you the gallons as well. either way you can't go wrong with any of those 3. lf you have any more questions feel free to send me a pm.