Technically not an altcoin but I'm going to go ahead and nominate CRYPTOKITTIES to the poll.
1. First blockchain game on Ethereum
2. First ever DAPP that, while pushing ethereum's transaction scaling issues, is a great example of why ethereum is a real working platform for smart contracts and dapps
3. Appealing to a massive demographic that allow's newcomers get familiarized with crypto in a fun and friendly way
Good game for two reasons:-
1. Good game.
2. Good demonstration of the fact that Blockchains can't scale.
Interesting idea. I have no idea of the distribution of these kitties though and no idea if they could be viewed as an ALT coin investment as the others in the OP. However if some others here think it should be added and can lay out the proposal as others have addressing the 4 key points then sure if people want it added lets add it