2.4GHz, which I only use for Vita, Wii U, and 3DS and very rarely even for that. All three are hacked so I keep them offline as much as possible, and the Vita uses ad hoc mode for remote play. Supposedly router makers wised up and started shielding the USB3 port after it was found to be a problem on the first ones that moved up from USB2. Not sure if that is the case with the TMobile/ASUS one though, since the shielded ones typically have the port on the side or front.
I had already ordered an ASUS RT-ACRH13 from Amazon before I saw the AC1900 recommendation here. 400+867 combined speed is already overkill for the tiny amount of wireless I actually use on my phone and tablet so I'm not worried about that part. I'm seeing elsewhere that the USB3 speed is about 60MB/s with Merlin installed on the 1900 and USB3 interference reduction disabled, less than half that with it on. No Merlin for the ACRH13 so I'm not sure if that's an option there (or it if it's even needed since that one has its USB3 port on the front). I guess I'll test it out and then decide if I want to return it for the AC1900.