I just replied to another thread saying how I like the CyberPower line-up so below is a copy of that. Also most 2200VA UPS that are for 120V usually have a 20A plug but if you keep the load low in relation to what it can support using an adapter like how I mentioned below you'll be fine. I keep my UPS at say 30% or less under full load though they're mostly idling.
I'm a fan of the CyberPower OR1500LCDRT2U / OR2200LCDRT2U (you can get a Nema 5-20 to 5-15 adapter for like $15) as they have both USB & serial connectivity. If you happen to run/convert to VMWare ESXi they provide a premade VM that can gracefully shutdown the hypervisor server (thus your FreeNAS VM) that is web configurable. You can also control outlet groups through serial/USB too.