Old Hickory is better for bass in my opinion but I definitely will agree with the floating debris. Be very, very careful with an outboard. I'm a kayak angler so I don't have those worries nor do I have to worry about the dirt shallow water but you certainly will have to watch for that. Percy Priest has much better Crappie fishing and there is also a fantastic population of Hybrids in there that can be a lot of fun.
Living close to Franklin, I'd recommend you go check out Williamsport. You are not allowed to use an outboard motor, only trolling motors, and man powered vessels are allowed. You can put a boat in there with an outboard but you're not allowed to use it. There are some nice bass in there and with the absence of outboards, it's nice and quiet. Great for me being a kayak angler as we often have close calls with the big boat guys not being considerate of us on the bigger lakes.