I'll go first.
My current portfolio:
Why I chose each coin:
BTC (Bitcoin) - Network Effect; Most Secure PoW Currency; Many Wallets and Services
bitBTC (Bitshares) - Derivative of Bitcoin
BTS (Bitshares) - Decentralized Exchange; Derivative Trading; User Issued Assets; Fast Confirmation Times; Dynamic Account Permissions (improved multi signature addresses); Decentralized Referral Program; Stakeholder Approved Project Funding; Readable Account Names; Voting
LTC (Litecoin) - Network Effect; More Wallets and Services Than Most Cryptocurrencies
BKS (BlockShares) - Decentralized Exchange; Bitcoin Dividends
NSR (Nushares) - Market Pegged FIAT Cryptocurrencies; Pays PPC Dividends
bitGOLD (Bitshares) - Derivative of Gold; Traditional "Safe Haven"; FIAT/Cryptocurrency/Inflation Hedge
SJCX (Storj) - Decentralized Data Storage
OBITS (Open Ledger) - Bitshares On/Off Ramp; Order book and reserves on the blockchain for easy auditing; Sharebot; Debit Card
bitSILVER (Bitshares) - Derivative of Silver; Modern "Safe Haven"; FIAT/Cryptocurrency/Inflation Hedge
NXT (Nxt) - Asset Exchange; Marketplace; Monetary System; Private Messaging; Alias System; Instant DEX; Multigateway
XMR (Monero) - Ring Signatures; Anonymity; A nice army of shills on BCT, which makes for good exposure
MAID (Maidsafe) - Decentralized Data Storage; Secure Log In
UNITY (SuperNet) - Multi-Cryptocurrency Wallet; Instant DEX; Multigateway; Telepods; Decentralized Market Decentralized Dice/Poker
SIA (Siacoin) - Decentralized Storage
XCR (Crypti) - Decentralized Javascript Programs
Why I own more Bitcoin than anything else:
I see it as being less risky than alternative currencies. It has a strong network effect (which dwarfs all alternative cryptocurrencies combined), the strongest (it's not even close) liquidity and volume, and a solid list of services, wallets, etc...
Why I own more coins from "long established" cryptocurrencies (or will eventually own.. my portfolio isn't exactly the way I'd like it right now):
I think that network effects are very powerful, and as a community grows so does a coin's utility, volume, liquidity, word of mouth, etc..
Why is each coin (except for Bitcoin) less thank 6% of my portfolio?
I see alternative cryptocurrencies as being quite risky, and I can't quite put my finger on exactly which ones will be the most valuable in the future. I prefer to pick general industry leaders that have a chance of becoming big time, and investing a small percentage in each one.
I personally would only invest in very few cryptocurrencies purely for the reason of them having a network effect. Those currencies would probably be BTC, LTC, PPC, and DOGE. Network effect drops off dramatically as you go to each lower tier. Bitcoin has much more network effect than the closest 3 coins combined. It is Bitcoin that is in the news all day and every day.
Most of the alternative cryptocurrencies I have chosen have (or are in the process) of innovating in some way. I try to stay away from copy and paste coins, and when I do buy copy and paste coins.. I only buy them in the "top tier" of network effects (see above).
I also think a fair release is pretty important, along with a solid set of active developers that back the project. Without a fair release the crypto enthusiasts can't get behind it- there is maybe only a couple exceptions I can think of. I posit crypto enthusiasts played a large role in Bitcoin's success. Also, without solid, dedicated, and active developers a cryptocurrency is doomed before it is launched.
I see long term value in Ethereum, but I did not invest in the IPO and expect the price to come back down to earth eventually. You will notice I invested in a similar project Crypti, which is much more undervalued at the moment. I generally stay away from IPO coins and new releases for around a year to see how the price is moving, the coin is developing, and how the community develops. Most coins in my portfolio I only purchased after long downtrends.
I currently have my portfolio weighted more heavily towards innovations having to do with decentralized exchanges than any other feature. I am not sure if this will change. I also see a lot of value in decentralized programming languages and data storage.
Edit: I recently sold my XRP because I realized there isn't a downloadable client any more and you have to register your identity. I might replace that part of my portfolio with Stellar, but at the moment I simply left it in Bitcoin.