I’d go with either a 75 or a 90. Both are big enough to be able to keep stable. Smaller tanks are harder. A 55 is a difficult footprint to work with. 60s have sucky dimensions to work with and you will be limited in the type of fish because of that. A 75 and 90 ar both the same width as a 55 but they are deeper (Front to back). That additional front to back size gives you an easier time maintaining it and the increased water volume will make it easier to keep stable.