I know this is probably sacrilege  to the OSR, but I don't really care for the Greyhawk box set with the Darlene map. Yes, it is wide open so you can do what you want. There's not really anything going on, which a lot of DM's probably love. However, it feels very bland to me.

I'd have to say my favorite version is the Player's Guide to Greyhawk, which was published for 2e. It's still pretty open, but a lot has happened. The world actually feels alive. The Greyhawk Wars changed a lot of countries, the Circle of Eight was broken and rebuilt, and Iuz became a god. The Scarlet Brotherhood is also a great villain.

Another thing I like about this version is that even the evil countries fight each other. Ahlissa and the Scarlet Brotherhood are fighting in Onnwal. Heck, most of the evil countries would fight Iuz if he got near them. There are active wars going on (the new Shield Lands and Geoff are the best examples of this), but large parts of the world are relatively peaceful, or at least a good spot for adventurers. Heck, the area right around Greyhawk City is loaded with stuff for players to do.

In any case, if I get to run another Greyhawk campaign, this is the version I'm using.

I also have the Living Greyhawk book, and I like it. I don't think it's as good, though. Maybe the writing style is too dry, or stuff changed even further as the timeline moved. I'm not really sure, but I don't like it as much.

The same thing are potentially present in the boxed set however due to the format of the product, it not covered in detail. In contrast by the time of the 2e Players Guide, the Greyhawk Wars have occurred with a wealth of additional detail.

I always loved Greyhawk myself, due to the fact that there just enough medieval, just enough history, and just enough fantasy to make for a darn good D&D setting. The only issues that I had back in the day, is what I called the "Howling emptiness of the 30 mile hex". Today, 30 years later, I have more than enough experience as a referee to make that a non-issue. But for my 16 year old self, it made the City State of the Invincible Overlord and the Wilderlands more appealing.

The result was my Majestic Wilderlands. One way to view my campaign is that it bolts together the broad ideas of Greyhawk with the details of the Wilderlands.

I like the boxed sets rather subdued tone. And really love the vast emptyness of the land since it left so much to explore or expand. Much like Karameikos. I REALLY do not like how both got later updates that to me overcrowded the landscape and tended to break up what had been established.

Never read the Players Guide. But I do have the Living Greyhawk Gazetteer which I enjoy. Sadly, as TS said, it is a bit dry and got mostly ugly or just plain boring artwork. But there is a serious amount of information in it. I prefer it to the original box. Except from the map. I have many times been thinking about D&D/OSR adventures in Greyhawk, but right now I use Forgotten Realms since my players have much easier to relate to that setting because exposure from other media. I like the medieval-ish tone in Greyhawk far more than the general Forgotten Realms "fantasy-fuckin-Wall Street" (but it does contain some interesting areas, I admit that).