That's a ford/chevy question. Depends on the environment you plan to hunt, how junky the site is, your tolerance for junk and false signals, the type soil minerals in your area, etc.. Heck, I can think of some sites where the best and most numerous finds will be made by a 2-filter cheapie machine (or a 77b which can be had for $50 on Ebay), yet those machines aren't power-house deep seekers. Then why would they come in first place at the end of the day in some hunt sites? Because they are the best at averaging out iron, seeing between and through nails, etc... Contrast that to some powerhouse machines, and they become problematic in iron-ridden sites.
So it all just depends! It's like asking "what's the best motor vehicle, no matter what the cost?" The answer would be "what do you intend to do with that motor vehicle? Haul rocks to a quarry? then maybe you need a dump truck. Speed? Then maybe you need a corvette. Low end torque for pulling out tree-trunks? Then maybe you need a beefy 4-wheel drive truck, fuel economy? then maybe you want a mini-cooper. Comfort? Then maybe you want a Lexus. So you see, it all just depends. Lots of machines find "coins and relics". And heck, some of them can get them balls-to-the-walls-deep (like the Fisher 1266 for instance). But they can become instable and unuseable in all but the cleanest mineral free environment.
Some have suggest the Explorer. And I would agree. But I have also seen newbies throw down this expensive machine in disgust, because the tooty-fluty orchestra drives them crazy! In those cases, the newbie would've been much better served (and thus find more) with an easy to use machine like the 6000 Di pro, or some other such turn-&-go machine. All too often a newbie makes the mistake of assuming "the more expensive, the better". Then they take this star-ship Enterprise machine, max out all the controls (lest they be "missing out"), and then wonder why it clacks and clicks all over the place!