My favorite Freshwater fish is a toss up between three of my all time favs.
A) Silver Arrowana, I know in asia they are regarded as 'less of a fish' than the asians, but I think their eel like bodies are just incredibly graceful and gorgeous... I have had two, both I kept until they were almost to big for my tank and then I returned them to the store. Always wanted to get a bigger tank and have a go at getting one full size.
B) Bichar Dragon, what a cool fish. Love the fleshy fins and the intricate design of their coloring. I have only owned one, he was 14 inches long when I sold him, and loved to eat ghost shrimp that I primed with good grub for a few days... my tank was heavily planted, and he loved to sligther through the 2 inch tall micro-sword bed I had covering the bottmo of the tank... he'd slip his head out of the grass, catch a glimpse of a shrimp, and stalk him to death! It was awesome.
C) One of the cutest but most rarely seen fish in my collection, was a black ghost knife. I have only seen three in all of Texas over about twenty years of looking, and now regret having sold him when I had to break down the tank... hope I can get another some day. Looks very much like a knife fish but does not get nearly as long, they are jet black and totally nocturnal. Hide all the time except the pitch of night, but a very cool fish none the less. One time, he hid for so long in my planted tank I thought he was dead, turns out he was coming out just long enough to snag a shrimpie and dissapear again at night... what a cutie.