My favorite minnow would be Blacknose Dace. They are active enough to make a tank come alive, but not hyper to the point I get dizzy watching them. They also come up and nibble at my hands during water changes. I love that. They are not the most colorful minnow out there, but I like more subtle fish. I also love the way their silver flashes in the light. I also really like Emerald Shiners.
My favorite small fish would be a Tessellated or Swamp Darter. They are so much fun to watch move around their tank and interact with each other. Plus, they are just so damn cute. LOL
My favorite larger fish would be a Green Sunfish. They have so much personality once they get acclimated to captive life, and will follow you around the sides tank when you walk by. If I stop and look at the tank, he is right there looking back at me. He is very sedate, and glides around his tank like he owns it (which he does). So far, he has not been nearly as aggressive as I was expecting, and is cohabiting with other greens and a smaller unknown sunfish. Plus, I like feeding him crickets and watching him slam the surface. I bet I could get him to jump out of the water for a worm. I'll have to try that.
I hate having to pick favorites like this! It's much harder than I thought.