and more specific, this one's an i5 https://www.amazon.com/QOTOM-Q355G4-Factory-Firewall-Multi-Function-Appliance/dp/B06XNWLR3J/ref=sr_1_fkmr2_2?keywords=pfsense+firewall+black-boxes+i5&qid=1553882807&s=gateway&sr=8-2-fkmr2
This one is a much better choice!
I'm going to get up on my soap box here... keep in mind, you should try to support the pfsense open source project as much as you can. With the Qotom box you found, you're only about $60 away from the "official" Netgate SG-3100 box. I'm not trying to guilt you into a purchase, and I'm not saying you're going to get a better experience with name-brand or not, but being that close in price, I would send my money to Netgate and the firewall project itself.
The biggest factor there is how much of that traffic will be over OpenVPN. If the majority of it is and you want to get anywhere near 2Gbps you're going to need the fastest CPU you can get hold of. Each OpenVPN process is single threaded so less cores at higher speeds wins here if you have only a few tunnels.