How can I place prefabs into a world and what's the best way to get them?

I'm making a rougelike platformer and I want to make a load of hand crafted rooms and like spelunky place them around. When the player enters a room a script will go off. The script will know what exits the current room has and what entrance was used (Don't need to place anything where the player came from). I then have 2 options for choosing what rooms will work:

I can either have all the prefabs contain a script with a list of all the exits they have, then check that list for if the right one is there. I.E; Entered room from the left. Room has left, right and top exits. I can ignore the left as that's where I came from, I can ignore the bottom as there isn't an exit there but I need to check the arrays on the prefabs to see if they have right and top in them. After that I'd place the top one x units above and the bottom one x units below (I'd also check something wasn't there before placing over it).

The other option is to have 4 lists of prefabs. A list for top exits, bottom exits, left exits and right exits. Then look through those for what I need. Then I would place the blocks where they needed to be from there.

So, as the title says, what of those options would you use for picking and how can I then get the prefab I need and place it into the world. I'll use a "Centre" item for it and then place the centre of the prefab a certain amount to the side of the current rooms centre.

Thanks in advance for any help you can give :)