I recommend getting one that's compatible with dd-wrt custom firmware. Check here:
DD-WRT :: Supported Hardware
Also look into dual-band, dual-radio routers if the laptop will use a lot of bandwidth. They broadcast on both G (2.4Ghz) and N (5Ghz) bands simultaneously so that your laptop can have almost twice the speed. If your laptop has a 802.11n Wi-Fi card, then it usually supports this.