Probably 80-90% of my fishing is for smallies, and really the best rod is determined primarily by the waters you plan to fish. I have a small local river where I prefer either my 5wt or 6wt rods, but I cast mostly streamers tied sparse. When I fish the Susquehanna, I nearly always use an 8wt. The fish are bigger, the flies are bigger, but most of all, the wind is bigger.
So clearly, you need to add a 7wt too.
You can never have too many rods.