I was never a fan of Forgotten Realms, and never really played in it, nor did I use it as a DM. I did use the original World of Greyhawk folio, circa 1980, and loved its incredibly huge world map, even if my campaign never branched far from the city of Greyhawk.
At college I found the D&D Known World Gazetteers, crafted for the Basic/Expert/Companion/Masters sets by Frank Mentzer. I adapted GAZ 1: The Grand Duchy of Karameikos for our 1e play, and have stuck with that setting ever since. It even lead me to shift away from AD&D (fully in 2e mode) to the BEMCI game.
I acquired (and still have) all the Known World Gazetteers as well as the Creature Crucibles and the Dawn of the Emperors boxed set. But the only setting I've actually used is Karameikos— though I borrow elements from the Ylaurum, Dwarves of Rockhome, Elves of Alfheim, Republic of Darokin, Thyatian Empire and even Orcs of Thar sets for use in my game.
Long ago I decided to ignore any "official" developments in a campaign world. TSR/WotC/Hasbro can declare all the wars they like and topple all the governments, assassinate all the leaders, and declare that magic is being drained from the world all they want— these things haven't happened and won't ever happen in my campaign, unless the adventurers themselves trigger the change, or at least participate. *I'll* decide if there's a dark conspiracy or a coming apocalypse. Greenwood and his ilk can make pronouncements all they want for their worlds— but once I start playing in it, it becomes mine, and the only changes which count are the ones I make.
I recently tried to read the 5e Adventurers Guide to the Sword Coast, and found it overly detailed, but worse, extremely boring. I gave up. Fortunately it was a library copy, so I wasn't out any cash.
While I have 5e and have played it, I prefer the flexibility and simplicity of classic D&D, by which I mean the BECMI series. I use the Dungeons & Dragons Rules Cyclopedia omnibus rules compilation from 1991, along with some house rules. Clean, simple, and fun.
By the way almost ALL of the original TSR rule books, supplements and accessories are available as PDF and POD from DriveThruRPG.com. These are legitimate, licensed releases by Hasbro/Wizards of the Coast. So if want to find the original World of Greyhawk, the original Forgotten Realms, the entire Gazetteer run, B/X/ECMI D&D, the Rules Cyclopedia, AD&D 1e, AD&D 2e, or any other edition, supplement, module or whatever, you can get anything you like. You can even have ‘em bound and printed, just like the original books.
It's a golden age again!