I really like undead, humanoids of varied and exotic types, plants/oozes/insects, and fey type things. Although I also like far realms stuff too, but rarely get the opportunity to use. Mystery, horror, and high flying action are big on my list of styles.
There is one specific plot (details the same) I've used twice for two different groups. Beyond that, it depends on the campaign, because some campaigns just don't work that way, and some groups have different motivations.
One notion I like (to which I used a lot in my last campaign) is the repercussions of player actions leading to further adventure. "You stop X, but the thing X was keeping in check is now unchecked" or "You stop X, but now there are after-effects of what X was doing" (for instance, bad guys opening up a rift to another plane, PCs may stop it, but some inhabitants manage to escape out the rift during the battle, and cause trouble later.)
I am a big fan of player decisive goals. Players going forward and furthering their goals. I like currying favor and trading favors, and that sort of nationbuilding.
A particular campaign idea I like a lot is "Players are in charge of something". I've ran a colony situation twice now. Or a campaign where the party is actively trying to make the world a better place, and choose which direction to go, what threat to tackle. I also like themed campaigns - a Detective game, a Thief's Guild campaign, a game where everyone is traveling gypsy con artists, etc. It gives me direction.
I avoid "Fate/Destiny", "Save the World" stuff (compared to, say, saving the town) and I dislike unmotivated "We just wander around and hope random adventure hooks unrelated to anything else falls on us" rather than pursuing certain things.
