I think it pretty much depends the type of water you are fishing and the size of flys you intend to throw. I tend to use a 6wt if the wind is not too bad and I am fishing a #6 or below. If the wind is strong or if I am using bigger flys, then the 8wt gets the nod. I think you also need to consider how big the fish are. Since all my smallie fishing is catch and release, I want to get em landed and released.

However I think Bob C may be spot on when it comes to the 7wt. I don't own one but have been seriously considering getting a 7.

Just my 2 pennies worth.