So much depends on your scoring system for ranking defenses. A good defense won't always translate into a top fantasy defense.
The Bucs obviously are the #1 defense. Bartber just scored, so that should help their so-far lack-luster point total.
Carolina would have to be the #2 ranked defense. Again, that doesn't always translate into points. Besides He Hate Me's, return, the Carolina D got me 1 point.
That ends the sure thing, power defenses.
I'd still have to put Miami up there at #3, but they might be on the downside. Again, most of this is points allowed /yards allowed /physicality of the unit. These generally translate into point over the course of a season.
Tough to say after 5 games. KC is the #1 fantasy defense in many leagues, mostly because of Dante Hall. Their D was horrid last year, and the haven't improved that much. They are better than last year, but not a great defense.
Seattle has scored on D a few times on D, New England seems to have a unique D that confuses teams. Dallas has been surprisingly tough. Denver, Cleveland, Indy are decent options, Philly or Pittsburgh could rebound for a good year.
D's are a crapshoot. I generally get screwed on defense, always playing the Seahawks when they score twice, etc.
Oh yea, about the Colts D. Duece ran all over them, now Pittman has posted a C-note on them. They are not a great D yet. They run Dungy's system, but don't have the horses to make it work like Tampa Bay.
The meek ain't gonna inherit $#!%....'cuz I'll TAKE IT!