Wouldn't buy Norton ever again. Don't get me wrong, Symantec is an amazing IT Security company, but their products are still not worth it even as of today. Also, it's low detection ratio would be enough to keep me away from it. Also, their sales support is TERRIBLE as they always try to sell you a higher package level whenever you want to support or to renew a product.
G-Data : Don't know enough about the product to make you a recommendation.
Trend Micro : Way too many false detections, just check the AV-Comparative tests. Also, I see more Trend Micro as a "business" Antivirus more than a "consumer" Antivirus so I wouldn't buy it either.
In my opinion, there's only two Antiviruses companies that are worth buying products for and they are Kaspersky and ESET. Yes of course Avast and Avira are also good Antiviruses, but they are good free Antiviruses, not paid. When it comes to paid Antiviruses, you'll want to go with either Kaspersky or ESET. Plus depending of you live, their products can be ridiculously cheap. 3 licences of Kasperky PURE 3.0 for $25. You don't see that everywhere.