Polypterus ornatipinnis. I've had on for 9 years now and I swear he understands some stuff I tell him. Recently got him some mates, another ornatipinnis and 2 Endlicheri. The Endlis are weird. Some of the strangest behaviors from them. The one I think is a short body will swim back and forth along the glass for hours, but then wear himself out and bury his face in the sand.
I also bought an Andinoacara aequinoctialis (gold saum green terror). At about 5" he is showing some great personality. Comes to great me every time I walk in the room. The polypterus don't both him in the slightest.
Last, I have 4 Hoplosternum magdelanae and they are a riot. Constantly active. Sifting through the sand. They eat pellet right out of my kids hands. Feed frozen blood worms and all of them will be sucking on your fingers trying to get them before they're even thawed.
In a separate tank, I have the female aequinoctialis because the male wouldn't play nice (I put him in the polypterus tank early. Was going to grow them out a bit more. Luckily he didn't become lunch). She is sitting right behind me while I'm typing this. Even she is beginning to show a great personality. She's a fighter. He got her pretty good on the sides and took off most of her caudal fin. She's pretty happy now (sides are fine and fin is growing back) and will act like she's trying to follow me out the door when I leave.