Just my two penneth worth. Don't just look at "Download Speed" in isolation. Also look at "Line Speed" i.e. the speed that your ISP is delivering broadband to your router. If there is a large difference between the Line Speed and the Download Speed there may be problems with the broadband setup at home. Dodgy ADSL filters or extension wiring, interference from other electrical equipment etc. If possible always plug your router into your "main" 'phone socket and not an extension socket.
Most routers will allow you to interrogate them to find the Line Speed and some speedtesters provided by ISPs will tell you as well.