The "optimum" choice of a router depends on what you'll be doing with it, and how often. Less expensive routers may suffice for occasional light-duty applications, and, as such, may represent a good value proposition. Better brands (translated as more expensive) will generally last longer, however, particularly if used frequently.
Most of us here are frequent router users, and generally lean toward the better brands as a result. I like the Porter Cable brand (purchased at an industrial tool supplier, not a home-improvement store), but others have their favorites which differ.
Among the smaller routers, the Craftsman dual-base kit has received good comments here.