I would be careful using one to buy the other, if they both 'crash' you'll lose out. Better to use Fiat to purchase.
Also whatever wallet you pick make sure its offline, buy and then get your coins off the exchange into a wallet you control.
https://www.ledgerwallet.com/products/ledger-nano-s supports both btc and ETH but that is for serious holders as it cost 70 eur.
Looking into ETH and might take the plunge, also worth looking at Golem GNT. i know somebody who trades as a full time job and these are the only ones he trusts having been burnt on all the other alternative to btc that sprang up.
But as mentioned i still think nobody knows for sure, its BTC maturity that gives me the confidence, but i am a user rather than an investor.