The X-T1 is objectively the better camera. For that little of a price difference, there's no major reason to not get it. Bigger EVF, full dial layout, weather sealing. However, there are a couple of small points in favour of the X-T10: "like new" suggests the X-T1 is used, so I would assume that does not come with a warranty, whereas a new X-T10 will; the battery life of the X-T10 seems to be very slightly better; if you trade in or sell your X-E1, that + the extra $100 would probably be enough to buy you another lens, if you fancy it.
Double-check the X-T1 really is "like new" and make your decision from there. If it really is as good as new, I think this is a no-brainer.
