Sorry for your loss.
I would go with a black. I have a 30" one now and it's awesome. No drop eye, calmer than a silver, and wont grow as big. Still I'm very careful when cleaning the tank. I have never cleaned the gravel in the 4 years I've had mine just for the freak out issues. I'm very careful when cleaning the acrylic just doing one side then waiting for the Aro to move and doing the other side. I even added a trickle system so I don't have to do massive water changes. Most Aros die exactly how yours did. I get a laugh when people say feeding this or that (mine loves mice) will kill your Aro.
6 years in a 125! You did very good. You will get 20 out of a calmer Black for sure, especially if your going to get a bigger tank.