I had using Tplink single antenna 54mpbs router since the last 4 years and its been working flawlessly. I have recently upgraded to a 300mbps router but not because of range, because of speed.
If you're looking to transfer large files for your home network or looking to stream HD movies across your home then you need a router with a higher bandwidth.
If you're living in an area where there are many wifi signals around then its better that you go for a dual channel router.
If you are using DSL connection and looking to hook up your dsl modem with the router then i would suggest that you get a single device and you'll get the best pings.
Range can be extended by connecting wired antennas and placing the router intelligently. If you live in a double story house , place your router in the exact center on the upper floor but close to the floor. You can also get two cheap routers , one for each floor you can use same SSID for both routers. Works well!
Remember the only reason you might wan't to get a really expensive Cisco or other fancy router is if you are looking to stream IPTV over WIFI. Multi casting on a non supportive router will clog your network and you will have to restart the hardware.