For the time being, Ethereum is the best coin to mine, even profitable at electricity of $0.2/kWh. But the price might drop and make it unprofitable.
He seems to don't have any current hardware, and with the end of the mining around this summer (at the same moment as the halving, by the way), I wouldn't recommend him to buy some GPUs just to mine Ethereum, since the hashrate is also increasing.