Nano and Dent seem like strong contenders for investment, though I am still doing my research on these as I don't fully yet understand the problems the tech solves or if there would be enough incentive downstream for buyers to pay a premium price on the tokens.
Nano seems to be doing the right things from a dev perspective. Great team, protocol updates are well tested and rolled out. Nano is being tested in gaming platforms with near instant, fee-less txs.... best currency right now.