I own a broad portfolio of currencies - about 20 or so. Mostly, I'm in ETH.
Looking for a few things. If you want blow-out potential, then you're looking for a platform type of coin (ETH, for example). ETH exists to build other coins and functions. I also hold KMD for that purpose. If a lot of new, useful coins are built on these platforms, the coin will rise manifold.) WAVES, Bitshares, AEON.
True currency - a crypto that can be used for buy and sell. Monaco (has an instant exchange visa card), ARK (point of sale), Iota (0 fee transactions, goes faster the more transactions occur in theory which overcomes a huge problem in the industry), OMG - all have potential.
Second, use cases. I'm currently working on a whitepaper for GETGAME (a game designers platform), built on the Openledger platform using OBITS (the Bitshares coin). The idea is solid - great market participants who want to play and love tech, an integrated platform style of coin that spawns other coins ad infinitum (most will fail, but the winners will carry the losers and the losers do not hurt the GetGame coin). Gaming also draws huge funding on crowdfunding sites - the biggest funded projects (25X the ask) are always games. It's the right market to tap and the right way to do it.
Also, insurance industry, legal industry, inventory tracking (Walton coin WTC does RFID and has a very large contract- a strong coin.)
DMD looks interesting - it's an older coin that stakes (you get coins for having coins) and has risen steadily for years - follow the trend.
Exchange coins - Binance is the best of these, but the market is way flooded.
Right initial market cap - Is it a trillion coins? That's an oversupply and a coin that will never, ever go up very much. Is it too low? only 5000 coins worth 5cents? The market will dismiss it.
Good team - are they experienced? Is there a holding period for founders coins provides incentive, prevents selling for quick money and killing the market)? Do they have pre-ico backers (savvy investors who see great potential)? Are they greedy - Ripple kept 60 billion coins themselves and put out 40 billion - who controls that market? (Don't buy XRP, imo -there's a shism with the founders and one has a LOT of XRP, but is in serious contention with the others.)
Investors - Iconomi has a digital asset array, but their coin is junk, imo. They just used it for funding and now aren't supporting.
Flaw in ICN is - coin is not integrated into the use of the platform. You can't even buy/sell their funds with their own coin. You have to use BTC/ETH. They threw their initial investors udner the bus, imo. At any rate, their fund is an easy way to diversify holdings and I think their fund coin is available on exchanges. (I have some on their platform).
Question in general is - Is the coin useful after the ICO or is it just a fund-raise?