I hate to say it, but your question ......... even with your clarifier of " .... in trashy areas", leaves lots of room for multiple answers still.
Because it will depend on what you mean by "trashy area". For example: do you mean "trashy" as in simply "iron ridden" (burned down houses that introduced reams of nails, etc...) where you still intend to be a hero and still dig every conductive item, even down to foil sounds? Or by "trashy" do you mean locations where modern stuff is over the top (new parks, or whatever) where you might intend to (gasp) pass foil sounds too, and content yourself with being a little selective, and favor deeper stuff, or mid-to-high level conductors, etc...?
And even with those answers, there's still infinate variables, because there's infinate trade-offs still inherent: For example, if you *truly* wanted a machine that kicked *ss in "trashy areas", there are some machines that could be recommended, that would effortlessly pull conductive targets from iron ridden zones, while leaving all iron, and not even being fooled by iron. But with those, you'd be limited on depth, and perhaps lack performance in moderate to high mineralized soils. You'd also lack good TIDs (but perhaps that's not important to you).
Or if you mean just random trash, and you've got a lot of patience to get fooled by certain shapes of iron, and perhaps you want some depth (like if there's tall grass and foilage you need an extra "umph" to punch through depth wise), then perhaps you'll want a machine that's a bit more of a powerhouse. Will it see through trash as well? No. But you'll do better in mineralization, TID, depth, and speed of ground coverage.
So there's just too many variables still. Kind of like asking "what's the best kind of car for me to buy, if I have bumpy roads in my area?" People would still have to ask you if you're intending to haul rocks and gravel, then perhaps you'll want a truck. Or if you're hauling kids to soccer practice, perhaps you'll consider a mini-van. Or if you want great gas mileage, perhaps you'll consider a mini-cooper or hybrid. Or if you want speed, perhaps you want a corvette, etc.. etc.. etc..