I have yet to make it to 4 Rivers because it is always packed when ever I drive by. Which is a pretty good testament to how good it is supposed to be. All the reviews I've read of it have been raves.
I have been to Blackwater and Cecil's and like them both a lot. They are south of downtown; both of them are off of South Orange Avenue.
Depends a great deal on whether you mean spare ribs or baby backs. Bubbalous' aren't bad. Blackwater's are good. Good spare ribs are hard to find unless you run across a good mom and pop place. There's a little Shack of a place on Geneva Road in Oviedo that serves excellent ribs.
Sorry I can't be more help.