Dell XPS vs Acer Aspire R15 for Wi-Fi

Can anyone tell me which of these two would be better @ utilizing Wi-Fi, including Wi-Fi at hotels, etc & at public rest areas along highways? I've read that Acer attempts to build into their laptops a superior ability to acquire Wi-Fi, but that their Wi-Fi isn't upgradeable on their machines. ..not sure if this is true or not. I know the Wi-Fi card on the XPS can be upgraded, but I'm not sure if it's ability to utilize Wi-Fi is as good as that for the Acer. I'd probably spend the extra coin for the XPS if I thought it a better machine either right out of the box or in the future in utilizing Wi-Fi, but if not I'd probably go with the less expensive Aspire.