A coin that hasn't been mentioned here yet, is the Steem Backed Dollar (SBD). This SBD is worth exactly $1, because you can convert SBD to STEEM at a rate of 1$ per SBD (with a delay of 3.5 days).

This would obviously only work if there stays a demand for Steem, otherwise you could convert it to steem, but then no one would want to buy it, but the current Steem Markets are very active and they're not going to fall soon.

More information on steemit.com