My last thoughts on looking at a few alt coin charts was LTC was surprisingly resilant over the last year or so.   I thought that was impressive, Im not sure of the reasoning behind it exactly but was surprised it appeared to fair better then ETH for example.   
ETH is probably part of a deleveraging story I guess though I also read my IPO had not in fact dumped coins as some might presume.   Also ETH would have done far better if those IPO had gone onto to be productive enterprises, 18 months or so is a bit soon to demand that though.

My personal take would be to recommend a POS or proof of stake coin because you went and used the word invest not speculate.   Holding plain BTC is really speculation not investment, mining and investing in equipment would be investment.   So this is why I mention POS because the plain holders of the wallets are always part of the confirmation network and receive staking fees which is arguable closer to the idea of investment.   ETH is apparently switching to POS? not sure on that progress to date