Based on the details, I will take the Lexus. It's far better built, has a standard V6, interior appointments are a few levels above the Mazda's, and hold value well. It is more better looking than the CX7s (in my opinion). It is less sportier than the CX7 tho, if you are looking for that. I think the price is high. Something in the sub-$15k would be a decent value.
However, you have not specified if the Lexus is a Prior Salvage title because of its Accident record (or if the incident, however minor, turns up in its Carfax report). If it is, do NOT get it, unless you negotiate it down to something you are very very happy with, AND plan to keep it around for a very long time (5+ years).
Also, check out the Hyundai VeraCruz, which whooped the RX in a head-on comparison when it came out.
In conclusion, unless you are in a terrible hurry to get a car, I say it certainly won't hurt to check eBay. Lots are sold by dealerships themselves, and prices end up being a few hundreds/thousands cheaper than what you can get at the local dealership.
