Bamf Comics
Fish Fanatic
Angels as already desired tend to hang in the middle anyway and get long flowing fins on some types that show great in a 55. Guppies love the surface but tend to meander all over the place. As the tank fills with growing fry, they'll be visible in all zones. Price is a big factor for many trying to jump from a 55 to a 75 which is just as tall. Same thing downgrading from a 75 to a 60 which I did to get the shorter tank height but paid more for the privilege. I wanted 15's since I'm already running a 15 for one guppy spawning tank but the 20 high sells for quite a bit less than the 15 so for now, no lids and leave the water at about the 15 gallon height range. You can go that with a 55 as well saving the cost of lids. That space can be filled with air or even later on plants that grow out of the top of the water table for future options.