Had both at one time, and enjoyed them both very much.
If I had to choose, ................ it would be the XLT.
Cortes was a great machine which I enjoyed using very much, but after many many hours using both, I just had more confidence in the XLT. After searching an area with my XLT I seldom researched that same area with another detector and found anything. If it was there the XLT found it. I could not say that with my other detectors with as much confidence. I also liked the ability to save different setups in memory on the XLT. More difficult to learn to use (longer learning curve) than the Cortes, but when you finally understand the machine,.......... it is a fantastic detector.
Don't get me wrong, as I said the Cortes was a great machine. Light weight, goes deep, easy to use, and less money than the XLT. A great machine I wouldn't hesitate to recommend. I just recently returned to detecting after being away for a few years. I got a nice deal on a Fisher Coinstrike and picked it up, ................ but, ....................... both the XLT and Cortes are detectors I am looking to find as soon as possible as well.
I think it is one of those situations where if you have one or the other you will definitely be pleased. If you have both, you might find some little things about one that you prefer over the other. You can't go wrong with which ever of the two you choose.