Mastercoin - doubtful how this approach of protocol layering prevents double spending.
NXT - Closed source implementation. Does anyone have any idea of how this actually works? How fair is the distribution when all coins were bought for a mere 21 BTC.
Colored Coins - Fortunately, they don't have a ridiculous buy in vehicle to support their work.
Bitshares - So these folks use a bitcoin like clone to raise funds. They are redoing everything from scratch. Anybody's guess that this even works out.
eMunie - I heard about it 6 months ago, not certain if their multiple simultaneous block chain forks really work.
Anyway, my plan for iXcoin (The Internet eXchange Coin) is dirt simple.
Stick with tried and proven Satoshi Nakamoto bitcoin technology and layer on top of it Colored Coins.
You forgot about Friemarkets. The proposal is very solid, they are going to develop it as a Bitcoin protocol upgrade (which is superior to colored coins in many ways, but requires much more work), and add it to Freicoin, the alt-coin. They have a competent team...
The only problem is that they are looking for $200k in donations to make this happen.