Simple answer, the MXT Pro. Naturally I'll ask what detector you have now and do you feel you need to make a change from what you're using?
To better answer I can say that I am not, and never have been, a DFX fan. I've owned four of them and they lasted just a short time because they never performed up to the level of my XLT. I have owned a lot of the XLT models, and have one in my current outfit as well. The original MXT came out about the same time as the DFX and I favoured it over the DFX to compliment my detector outfit. When Carl worked on improving the design to give us the MXT Pro, I immediately got it to replace my MXT. The MXT Pro is a very efficient detector and works great for Coin & Jewelry hunting.
Even more so today because a lot of sites had become trashier in the last 20 years and the 3 filter design of the MXT series is better because you can use a moderate to fast sweep in open areas yet still work with a slow and methodical sweep when hunting trashier environments.
I have a very versatile outfit of detectors right now, however if I had extra money and wanted to have a museum of favorite detectors through the years, I would get another MXT Pro with my two favorite coils. The 6 1/2 in concentric and the 9 inch concentric spider coil. Great for trashier or brushier your environments and the other for working more open areas.
Monte