Antminer S5 is the most cost effective miner at present. With a power draw of less than 600 watts at the wall anyone can use one at home. You would not want it in your living room or bedroom due to fan noise though.
I don't think you want them anywhere inside your house at all from how loud and hot they are.
If you are running in a area where you are worried about noise you might check out the Avalon 4.1 it's amazing on underclock how quiet it gets.
Shameless plug to new review I did on it:
https://bitcointalk.org/index.php?topic=1008726.0The S5 is also a great machine. You just you will need a spot that you are not using to put them that can keep noise away from living quarters, that's what I did with them.
I was also thinking of an sp20, I have read they are not even as loud as the S5 and out hash it.