The X-Terra 70 and the Explorer II, and it's not because this is a Minelab X-Terra Forum. I'm not hesitant about commenting on any make or model on any forum when an honest opinion is requested.
I can guarantee you that the X-Terra 70 is one of the most versatile "multi-purpose" detectors on the market today It is lightweight, well balanced, and it provides the operator with ample adjustment functions that are easy to understand, and it can achieve some very good depth of detection. The quick response and recovery makes it a joy to use for many applications. The only thing lacking with the X-T 70 isn't really it, but the fact that they need to get a smaller coil released for working trashier sites, but that should be soon .. we hope.
As for the Explorer II< is is not what I consider to be a "multi-purpose" unit. Definitely not my pick for a competition hunt, or for prospecting, and really not what I would pick to work typical gold jewelry producing sites. It is heavy, poorly balanced, and requires an ultra-slow sweep speed and is not very forgiving if you get sweeping too quickly.
However, in my opinion, for what it's worth, I believe that the Explorer II is the best detector on the market today for the detectorist who wants to put in the time and effort to do some serious $ilver $hooting. The Explorer II's strength is that it will give better Target ID info to a greater percentage of its overall detection depth, and for working old parks, schools, courthouse lawns and similar sites to go for the older and deeper coins, it is tops. Period.
So, in the end, you have to decide which application(s) you plan to use a detector for. Keep in mind, too, that most serious detectorists eventually have at least two detectors to compliment each other.
Monte