This question is a bit subjective. So I think you're going to get somewhat subjective answers.
Of the two the Sonicwall box is the more powerful device. You don't mention how fast the WAN connection or the number of clients on the LAN that you're trying to protect with this solution but the SonicWall will let you grow more than the Netgear solution.
For that reason and the fact that Sonicwalls are known for their ease of administration and have a great reputation I would go with that solution if given the choice. Sonicwalls also comply to standards so getting them to interop with other IPSEC implementations isn't too difficult if you ever need to setup a site to site VPN with a different device. They are also pretty standard gear so finding someone who has experience dealing with them shouldn't be too difficult should you move on to a new job.
Netgear on the other hand in my experience are entry level gear. They have been improving in recent years but I've had enough issues with Netgear equipment that I would be very reluctant to rely on it for something as critical as the network gateway. I can't really comment on a modern Netgear gateways. The last Netgear gateway I had to work with was an older Netgear VPN router/gateway and it wasn't a very good product. It worked but had a number of interoperability issues with it's VPN implementation and it's NAT functionality would stop working for no reason from time to time requiring a reboot.