It's not the brand, it's what detector will do
As much as I'd like to give you a brand or a specific detector, I won't because brand/model isn't necessarily your first consideration here. That consideration would be what features you should be looking for to shop for the right detector for **the types of areas you want to hunt.** That's why a lot of guys own more than one detector, or even *type* of detector -- because there's no "one detector fits all" detector.
The types of places you want to hunt for the type of stuff you're looking to find means you're going to find yourself in areas of lots of trash -- everything from old pull tabs to old coins to bottle screwcaps to roofing nails and everything in between and varying depths. And believe me, any old site will be LOADED with junk. You say you're interested in everything from old iron to coins. Well, that's a HUGE spread, and unless you want to spend 99% of your time digging huge, deep holes to dig up a chunk of 80-year-old sewer pipe, you're going to spend an inhuman amount of time digging tons of junk that isn't worth anything to anybody. Especially since lots of old homes on any street have seen 50-100 years of home improvements.
If you want to dig positively everything you come across, then it pretty much doesn't matter what brand or model you get. They all work great in All Metal mode. If you want to get picky (one day you want to dig everything, one day you might want to just cherrypick silver coins), then a detector with good trash separation is what you're looking for. If you're going to be digging old places with nice lawns, a detector with a meter is the best way to go because it's good to have a better idea of what you might have as well as the depth -- and believe me, no homeowner wants to see you digging giant deep craters on the lawns they spend tons of money to maintain. If you're going to spend most of your time in forested areas or on the beach (where digging deep holes isn't much of an issue), a solid detector without a meter is an economical way to go.