I chose option 4, so here's my explanation.
I don't buy many fantasy settings. I have the D&D Gazzetteer (for Greyhawk) and the Living Greyhawk Gazzetteer. That prompted me to buy the OOP Greyhawk, The Legend Begins 2e book (I think that's the title). Otherwise I don't have a fantasy D&D setting that I've kept. For example, I had Skull & Bones, but I left off my Pirate D&D game after running Green Ronin's free adventure plus a couple of conversions. My thinking is that the core D&D d20 rules get fantasy done right, so a setting that adds a bunch of new classes, races or other rules isn't compelling to me.
But, I do like other non-fantasy settings: Omega World, Judge Dredd & DragonStar. Adventure support is critical for me. And the need for modules increases as the new rules presented increases. I like the Horizons line, but I only ran Spellslinger as a mini-campaign with a few converted Dungeon adventures. I'll probably never run the others because it's just too much work.
I really like the concept of Ancient Kingdoms: Mesopotamia. It's a setting sourcebook and adventure module in one. I wouldn't even use most of the new rules presented and run it closer to a core D&D game if I ever do run it. Last Hero in Scandinavia is another module with great setting flavor. These are the ideal products for me.
As another example, I only picked up Grim Tales after buying Slavelords of Cydonia. I'll probably not run it as it is a little too complex, but my interest in the setting/rules book was only pormpted by the adventure/module book.
A setting presented without adventures just isn't appealing to me. Ideally, the advenutres are the setting; but that model is rare.