I agree with nazerine (welcome back, BTW
), if you want to do a sump definitely look into a herbie style drain. Durso's can be good too, but seem more fiddly IMO.
AIO is nice because you don't have to worry about plumbing as much, but it's sort of wasted on a tank of that size... you'll likely want to have a decent bioload (I would want a number of medium sized fish if I had a 50 gallon) and that will require a good skimmer which would be a pain to make space for in an AIO set-up. Also, if noise is a consideration things like skimmers are pretty noisy and you'll want to enclose that in a cabinet of some sort, a sump seems like the best option.
Just on the offhand what are the dimensions of the tank?