I have them all, really adds lots of meat to skyrim.

The way I see it...

dawnguard- KotN new extended quest and areas

Hearthfire- little rp/ housing dlc. Still wanted a tomb of my very own, or a mountain castle like some mods have (cause I'm an xbox user)

Dragonborn- my favorite, awesome new world if somewhat dissapointing quest. (I am Miraak, I will return and force you to build my temples! Muhahahaha! He felt like a stereotypical villain that Buffy the vampire slayer would defeat in the prologue to the actual show)

Should be option in PC category for "Legendary Edition" eg. base game & all expansions. I had to tick 4 boxes for essentially one vote. Don't know why PC only players have to tick PS3 & Xbox option "I play on another platform" . I mean if you only use PC, then only vote in that section...

I got Hearthfire because it was on sale for $2.49. I figured that if nothing else eventually I would run across a mod I was interested in that would need it's resources. After playing it, though, I did enjoy it more than I thought I would.