For your second unit by the non-wifi version. It is less expensive. You can use your timer on your phone to track the run times. Sure, you will not be able to see the actual run temp if you have it running while away from home but that is really only a minor inconvenience.
One of the best things about the Anova is it works perfectly well without being connected to a phone. I have other sous vide devices that are required to be connected. They are not reliable because they rely on connectivity. Phone apps Wifi and the like are not entirely reliable. To many links in the chain to go wrong. My point is that the Anova is reliable because all we really have to do is plug it in, dial in the temp and set a timer and it works without the gimmicks of phone apps and other technology. Those gimmicks are nice when they work but even nicer when they aren't required to operate.