I expect this to pan out much like the Pearl Jam poll. First two/three albums will get all the votes.
Purple is actually the one I listened to first and I liked it well enough, but I heard the first three songs of Core at my best friend's house and I was like OMG HOLY FUCKING SHIT. Granted, this was almost a decade after the album had come out and Wicked Garden had already been used on a car commercial and I had heard Sex Type Thing hundreds of times on the radio. I just remember hearing Dead and Bloated and being like, "Wow, this song ROCKS" and then hearing Sex Type Thing and thinking, "Holy crap, this song too?" and then Wicked Garden came on next and I pretty much ruined my pants. For a good amount of my freshman year in high school, I listened to Core an average of three times a day.
That's why it might come as a surprise that I picked Purple. It's just the better album from start to finish.
As for the rest of their catalog, I hated Tiny Music when I first heard it, but I grew to love it, except for "Art School Girl." Fuck that song. I thoroughly enjoy both No.4 and Shangri-La Dee Da as well, the former more so. "Down" is such an awesome song to just bang your head to.