I think you'd have to wait until the next Nexus' release before making that decision or putting any weight into what anyone else says. Nobody here knows anything about it yet.
One word. Updates. I would definitely choose the Nexus 4 for that alone.
Moto X will still (most likely) get updates from the carriers. A Nexus phone will get updates much faster directly from Google.
And if the X is like other recent Motorola phones, it'll have a locked, encrypted bootloader making ROM flashing potentially problematic.
What you won't see, however, is a Nexus phone running on Verizon (which the Moto X will do). The VZW Galaxy Nexus was a joke which languished without updates for ages while the GSM unlocked GNex received prompt updates from Google. Why VZW has to be this way, I do not know.
Witch would you get?
I have decided I am not buying anything but Nexus devices when it comes to Android.
The Moto X doesn't interest me. I will be waiting for the Nexus 5.
I was thinking Nexus 4 2013 just like the nexus 7 2013 I don't think they will make a 5" phone
The Nexus 5 will likely be made by LG and will likely be based on the G2. Expect a Nexus 5 and not a 2013 Nexus 4.
I'm going with Nexus 4 (2013). Google isn't going to mess up their Nexus branding. (Nexus 4, Nexus 7, Nexus 10)
A Nexus 5 wouldn't mess up their branding and would only show that they will continue with using numbers.
The new Nexus 4 without a doubt.